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
Well… this escalated quickly. 😳
Drove 3 hours to Metropolis, Illinois to get this X9 back in the field during harvest.
I think you can see what the problem is. 😂
Two new tracks later… she’s back in business!
NEW VIDEO TOMORROW AT 2 PM CT!
This one is going to be a GOOD one. You don't want to miss it!
Keep that green iron moving!
1 week ago | [YT] | 125
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ZK MasterTech
THE THIRD AND FINAL X9!
We inspected three X9s on one farm, and tomorrow we finish our repairs on the LAST one!
This one has a little bit of everything — pre-cleaner and chaffer work, a feederhouse repair that turns into pulling the entire top shaft, electrical diagnostics, a starting problem…and then we investigate the issue that had the customer REALLY concerned about this combine. 👀
We pull the engine shields and FOUND IT!
Then we check back in on the FIRST X9 we repaired — already harvesting with an 18-row corn head in some seriously DOWN corn! 🌽
New ZK MasterTech video goes LIVE Saturday at 2 PM CT!
One last X9. Let’s get it DONE!
2 weeks ago | [YT] | 384
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ZK MasterTech
Harvest is officially HERE! 🌽
We've got THREE John Deere X9s on one farm, and this week we're knocking out the repairs on the first two.
Hydraulic problems, electrical issues, feeder house repairs, separator drive problems, grain loss sensors… there's a little bit of everything in this one.
And before the video is over, one of these X9s is headed straight into the corn!
But we're not done.
X9 #3 is still waiting for us—and it has the biggest job of all. 😳
NEW ZK MASTERTECH
TOMORROW @ 2 PM CENTRAL
3 weeks ago | [YT] | 315
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ZK MasterTech
NEW VIDEO TOMORROW @ 2 PM CENTRAL!
12 GAUGE IS BACK… and HOLY MOLY is back in the shop!
This S780 came to us with THREE HOLES and a laundry list of other problems. Tomorrow, we're throwing the MasterTech treatment at everything we can before this combine heads to the field.
And this one has some GOOD stuff:
Full shoe auger bearing rebuild
How to PROPERLY set bevel gear backlash
S7-style feeder house drum stop upgrade
Grain loss sensor testing & diagnosis
New Milwaukee tools getting put to work
And a pile of other repairs along the way...
By the end, we've fixed just about everything we can.
Except ONE HUGE problem. 👀
“We Fixed Everything We Could on This S780… Except ONE HUGE Problem”
🟢 TOMORROW — 2 PM CENTRAL
Who’s ready to see 12 Gauge back in action?! 💥
4 weeks ago | [YT] | 331
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ZK MasterTech
Something isn’t adding up on this S770… 🤔
The cleaning fan is only supposed to run 1350 RPM MAX.
This one was showing 1430 RPM. 😳
It also had an RC1 power distribution code, a blown F12 fuse, and the fan speed wouldn’t adjust at all.
But WHY?
Instead of just throwing another fuse in it, I tore into the cleaning fan drive system to find out what was actually going on — and found more than one thing that needed attention.
Then after I thought I had everything fixed… I heard a squeak. 😂
🟢 NEW VIDEO TODAY AT 2:00 PM CENTRAL!
We’re getting this S770 ready for harvest and keeping that green iron moving!
1 month ago | [YT] | 202
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ZK MasterTech
Who's ready for some green iron wenching this Saturday?! 💪🏼 Got a good one cooking for you! Two Places Hydraulic Oil Should NEVER Be in an S-Series Combine - going LIVE Saturday 8/22 @ 2 pm Central.
1 month ago | [YT] | 332
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ZK MasterTech
New video is LIVE! 👊
https://youtu.be/MxPSpogbch0
We’re back on the S680 and now comes the hard part — putting the cleaning shoe back together the right way.
We install the sieve and chaffer frames, pitman arms, return pan, set the shoe drive shaft depth, talk timing and sequence, check clearances, replace a badly worn vertical auger, knock out feed accelerator bearings… then it’s finally time for a test drive.
After that, ROCKY gets his new Kondex concaves installed and leveled, and I give you a look at next week’s project…
9870 STS. Best combine Deere ever made?
1 month ago | [YT] | 265
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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
2 months ago | [YT] | 14
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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!
3 months ago | [YT] | 316
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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 months ago | [YT] | 353
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