Allister ARD garage door opener issues

Have two Allister ARD's installed in a 2 car garage. One stopped lifting the wooden door. The motor would just hum but not lift. A cable had torn, so I replaced that. Still wouldn't lift, so I swapped the motor from the known good opener, butit made zero difference. Swapped the capacitor. Door lifted and closed but stopped at times. I suspect its an issue with the motor controls, but the ARD system is old and doesn't have a single circuit board containing everything on it. It appears to have a seperate power supply, etc. Is it possible to obtain these components anymore since its an old unit or possibly upgrade it to the ARD II or IIa? Any insight would be helpful.