This modern stuff is very expensive and difficult to troubleshoot.
Even knowing its out of warranty, I would still be an unhappy customer with a 6-year old tractor that probably cost $50k, and facing $10k+ in repairs and still no resolution.
I have a similar story about my wifes buick. Bought at a local dealer that touted "lifetime" powertrain warranty (through a 3rd party of course). 30k miles and 2 years old it had the coil pack fail. $200 ~45k miles and 3 years a wheel bearing out. Few weeks later battery goes out. None covered through GM or the 3rd party warranty.
About 55k miles and 3.5 years the t-case output seal is leaking. Not covered under 3rd party "lifetime drivetrain warranty", but GM did cover this one.
Then at ~60k miles and 4 years some strange things started happening. Randomly about once every 30 min the thing would just be gutless and start bucking and wouldnt get out of its own way. Took it to dealer and they reflashed ECU and said if that wasnt it then the turbo is going out. Well, ECU didnt fix it, but I didnt believe the $1500 turbo was the problem. Spent a day with a blue-driver (app based scan tool) and made all kinds of charts to decipher. Every time the issue occurred, The throttle body was NOT being commanded to be open even though throttle pedal position was at 100%. (no throttle cable:banghead

. And the turbo wastegate was NOT being commanded to be closed and allow boost to build. I was convinced the issue was electrical/ecm related, and replacing a 100% mechanical component (the turbo) would not change the fact that the throttle body was not being told to open. Yet they still insisted the turbo was the problem. And wanted $1500.
I did get them to agree that if the $1500 did NOT fix it....that the $1500 would then go towards the actual problem and balance to be refunded due to their lack of diagnostic ability.
It never got that far and we decided on trading it in. Which lead into another dealer issue. We traded for a jeep compass, and after about a year started to have a audible "clunk" in the driveline under acceleration at about 30mph. But otherwise was flawless.
Took it back to dealer....said 99% of these drivetrain issues are solved with a reflash of the DTM (drivetrain control module), TCM and ECM. However the TCM and ECM are covered under warranty but the DTM was not and that would be $150. ($130 for diagnostic and $20 for the flash).
Guess what, didnt fix the problem.:banghead:I questioned the $150 last time and why I was paying for diagnostics on a warranty repair. And they said "We waive the diagnostic charge if we find a legit problem covered under warranty otherwise everyone would be bring in vehicles that are under warranty just for us to go through to give a customer piece of mind and we would never make money". Long story short: They ended up replacing the rear differential and the valve body in the transmission under warranty....and I made them credit my $150 back the first time for failing to diagnose the problem and charging me for something that didnt need done.
But that seems to be the SOP anymore at dealers. They cant figure out a problem so start throwing parts at it in hopes of getting lucky, all the while charging the customer along the way for unnecessary parts.
And the sad part is everything is a freaking computer anymore, or controlled by a computer so it is impossible for owners to make their own repairs. Heck, you cant even trouble shoot something as simple as a window not rolling down anymore because its all controlled by the BCM (computer).
As to the OP and his
L6060. However this all works out....at the end of the day I would not pay for any part that wasnt faulty. If this ultimately comes down to a wiring issue, bad ground, etc I'd be expecting a hefty refund of all the parts the guessed at. Its not the customers job to pay for a technicians education