Have not checked the aux M contacts as it will run without fault with the gov encoder disconnected. It doesn't log a drive error.
What does the Debug Screen show under Motion Excuses while the unit is faulted?
Dragging/sluggish brake (already mentioned) will cause a 27.
Flakey brake switch (if used) will generate a 27/26 fault.
Bad contacts, broken wires at Brake relays (SB, SB2 I think).
Faulty Brake Pick issues typically appear in Motion Region 2 or 3.
Bottomed out I_DRV_VEL to lowest setting of 30 FPM and car ran in one direction without fault. I could then get a better reading on screen 3 in Motion info to compare the Vcmd, Vfb & Venc. car was still reading about 7 FPM higher on Venc = 34 compared to Vcmd.= 27. Compared to another car running same I_DRV_VEL speeds were only 1-2 FPM different.
Thanks to all of your suggestions I began looking at motor parameters, specifically the PPR of the motor encoder, which was set correctly according to the job parameter sheets, and param 558 ME Base Speed. I first tried changing the encoder PPR param 609 higher and lower but it didn't seem to have much affect. Granted I didn' make extreme changes as I didn't want to set the car on the safeties if I could help it. So I changed it back and lowered ME Base Speed from 850 to 700 and the car ran up and down on inspection without fault! I gradually brought the RPM higher until it faulted again and left it in a happy medium at 750. At that point we were able to get a floor table scan and run the car on automatic for the first time in a long time.
Here's where it gets even more interesting. On automatic the car was running in the high 370's with a M_VEL set at 350 and yes just clipping the over speed switch on the governor. Dropped M_VEL down to 325 and car still running high 350's. Dropped M_VEL to 300 car is running in the mid to high 330's. The other thing I notice is that the car seems to be overshooting the pattern a bit, not really noticeable in the car but you can hear it in the machine.
Put the car on a heat run, top to bottom for an hour or so to get things warmed up. Car ran fine, not overshooting floors or logging any faults. For now I am happy the car is running but I would like to get to the bottom of why I had to make those changes! My gut is telling me that even though the encoder tag says 2048 on the motor and 240 on the governor there is some difference between them and the original ones! I could probably make some more adjustments to param 609 and maybe get the car running a little better but not going to mess with it for now.
Anyone have any thoughts on this? I REALLY appreciate all the help and suggestions along the way.