Welcome to ZK MasterTech.
Follow Master John Deere Ag Technician Zeth Key as he takes you behind the scenes of diagnosing, repairing, and rebuilding some of the most advanced farm equipment in the world. From massive 9RX tractors to S-Series combines, this channel shows the real work required to keep modern agriculture moving.
Zeth is a 2007 Automotive Graduate of WyoTech in Laramie, Wyoming and a 2023 WyoTech Hall of Fame Inductee. He currently works for Sloan Implement in Atwood, Illinois, bringing over 16 years of experience servicing and repairing John Deere equipment across central Illinois.
ZK MasterTech gives viewers an inside look at the technical side of agriculture — real diagnostics, field service calls, major repairs, and the problem-solving it takes to keep farmers running.
If you enjoy seeing big iron torn down, diagnosed, and put back to work, you’re in the right place.
Subscribe and follow along as we keep that green iron moving! 🔧💚
ZK MasterTech
Meet ROCKY. 🥊
After SEVEN videos over the years, I finally realized this S680 combine deserved a name. It just keeps taking a lickin’ and keeps on tickin’!
In today’s video, SHOP DOG CBX and I inspect an S780, then take a trip down memory lane before introducing the newest legend on the channel… ROCKY.
Question for you guys…
Did I finally pick the right name? 👇
https://youtu.be/5wLUWPRH2qE
1 week ago | [YT] | 13
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ZK MasterTech
The X9 projects continue!
New video drops today at 3 PM CDT!
Last week we tackled the major rock damage on one X9, but the job wasn't finished. Today we head back to get it wrapped up before returning to the shop for one last push on another X9 that's sold and needs to get out the door.
Four major jobs stand in the way, including rebuilding a damaged rethresher housing after something made its way through the machine. This one has a little bit of everything.
See you at 3 PM!
2 weeks ago | [YT] | 315
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ZK MasterTech
Back in the saddle and we've got a couple X9 combines that need to be ready for wheat harvest in a hurry.
Started out chasing a vibration issue and replacing a feederhouse drive sheave assembly. Then we moved on to another X9 with some pretty serious rock damage in the discharge beater area. The deeper we dug into it, the more damage we found.
To top it all off, severe storms and tornadoes rolled through Central Illinois while this was all going on. Thankfully we came through it without any damage at home.
New video goes live at 10:00 AM. See you there! 💪
Keep that green iron moving!
3 weeks ago | [YT] | 352
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ZK MasterTech
I'M BACK! 😎
Vacation is over, and the brand-new Summer Service Calls 2026 series starts with a bang.
While I was gone, the shop stayed busy. Big projects got finished, major repairs moved forward, and somehow an 8R fuel tank replacement turned into one of those jobs where it feels like you remove the tractor from the fuel tank.
New video goes LIVE today at 3:00 PM Central!
Who's ready for another summer of keeping that green iron moving?
1 month ago | [YT] | 345
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ZK MasterTech
Enjoying the music in my videos?
I've had a lot of people asking about the songs I've been creating, especially the Memorial Day song "Green Iron Stands In Honor," so I put them all together in one playlist.
This is the ONLY place you can hear some of these songs!
There are also several unreleased songs in the playlist that haven't appeared in any videos yet.
Let me know which song is your favorite!
suno.com/playlist/fbcb4fd3-4f93-4623-81ca-bc0f3956…
1 month ago | [YT] | 100
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ZK MasterTech
IT’S LIVE! Series finale!
While I’m taking a few days off with the family, I put together something special…
The BIGGEST moments from Spring Service Calls 2026 all in one place!
From the rare John Deere 8560 Navy tractor, to catastrophic transmission damage, emergency Memorial Day service calls, storm damage repairs, fuel system diagnostics, and some unforgettable moments with Ben — this one has a little bit of everything.
If you’ve been following the series all spring, thank you for riding along. If you’re new here, this is a great place to jump in and see some of the craziest repairs and service calls we’ve tackled this season.
Grab a drink, kick back, and enjoy nearly an hour of Spring Service Calls highlights!
The Most EPIC Moments of Spring Service Calls 2026!
https://youtu.be/1mCd_8y96Z8
👇 What’s YOUR favorite moment from Spring Service Calls 2026 so far?
1 month ago | [YT] | 193
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ZK MasterTech
🚨 EMERGENCY MEMORIAL DAY SERVICE CALL 🚨
Most people were enjoying the holiday... I was loading up the kids and heading out on a service call.
This John Deere 9620RX lost BOTH axle lube pressure and charge pressure while driving down the road and came to a complete stop. 😳
After getting the park brake released and the steering system into backup mode, we had to tow it to safety and begin diagnosing what appears to be another major pump stack failure.
We also make more progress on the storm-damaged 9360R back at the shop.
The new video is LIVE NOW! 🚜👇
https://youtu.be/_pFjLUOkKS8
1 month ago | [YT] | 334
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ZK MasterTech
NEW VIDEO drops at 2 PM CST! 👀
Planting season chaos continues…
One tractor suddenly dies in the middle of the field, another has multiple electrical failures, we chase DEF codes on a 9620RX, test out some brand-new Milwaukee tools during TOOL TIME, and finish the day replacing an A/C compressor on an 8RX 410 so the operator can finally cool off again.
This episode had a little bit of everything 😅
See you guys at 2 PM!
And as always… keep that green iron moving!
2 months ago | [YT] | 321
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ZK MasterTech
Rain’s got everything shut down… so we’re bringing the shop to you today.
New video drops at 2PM 👇
We finally tear into the 9RX 640 transmission and see the damage we’ve been waiting on. I go through it with Paul and we break down what failed and what we’re dealing with.
Ben rolls in a brand new 412R sprayer and we go over all the tech during pre-delivery.
I’ve also got an X9 1100 combine in the shop getting a full inspection to be field ready, plus updates on the storm-damaged 9360R and 9530T.
We check out the Milwaukee M18 handheld vacuum, put the Shop Dog CBX to work on the X9, and wrap it up with a look at a brand new Chevy 6500 4x4 service truck with a Knapheide crane body 👀🔥
No service calls… but plenty going on in the shop.
Video drops at 2PM — don’t miss this one.
2 months ago | [YT] | 452
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ZK MasterTech
Spring Service Calls are BACK with EPISODE 3 and this one gets deep 👀
We went to check on LT. DAN’s brother — a 9RX 640 with a 15.0L Cummins that cranks but won’t start… and it turned into a full starting system deep dive. Bad starter, relays on order, and breaking down the entire circuit so YOU know what actually happens when one won’t fire.
Then we roll into more service calls — including a 9510R that absolutely ate up some time 🔧
And the big question…
💸 Will $24,000 worth of injectors finally fix it?
Go watch it now and tell me what YOU think is really going on 👇
6 Breakdowns… Oil in coolant, broken gears and a major injector job
https://youtu.be/GF8UL61ynSU
And as always — keep that green iron moving!
2 months ago | [YT] | 349
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