A few suggestions to try, drive board is most likely a Fuji Electric FRK?????, it drives a 3 phase motor with an encoder on it. there should be a few little red LED lights on it, when the motor tripped off on error, the LED lights should tell you why by lighting certain lights, there will be a legend right on the drive unit.
Some of the codes are:
UV = under voltage
OV = over voltage
ET = encoder trouble
OL or OC = overload (too many amps)
OS & US = over and under speed
If the error is OL, it means that the motor is pulling too many amps due to many possible reasons, some of which may be mechanical issues, such as bad roller bearings or bearings with dried coating in them, coating in the gear train, worn gears on the end of the rollers.....
Check the coater drive clutches as well, there are 2 clutches for the standard 3 roll Komori coater. one clutch turns the rollers when the press moves mechanically, the other clutch is geared to the motor and turns the rollers via the motor running.
With the coating motor off, If you can INCH the press and at any time the applying roller does not turn then the clutch between the blanket cylinder gear and the applying roller has a problem. Also with the press OFF and the coating motor OFF you should be able to spin the applying roller by hand freely in one direction and not the other.
Similarly with the press stopped, anytime you start the coating motor and the rollers do not turn is an indication of a problem with the motor clutch.
Hope you get it fixed. Forgive me if my info is a little off I did it from memory my Komori tech documents are not handy as I don't use them anymore.
