PCF is position control failure
Vmode5 is a timed slowdown and stop that is due to the pcf.
Knowing what you have changed I would look to your power amps and feedback circuit. Megging your motor and gen fields. I'm sure you have made sure all your brushes are in good shape. Your ppt knew it was in the pit so I wouldn't think it was that. If you have a pvt change it. No other faults were on the 40 test? If you didn't know you should record the fault log40 test and 200-2 and 200-4 before you kill the power.
