DIY rebuilding can work days, week to years because everyone has done a different whether or not they know plus how much use matters.
If you have Delrin pins, output shaft or gear could be dying... http://www.fiero.nl/forum/Forum2/HTML/128600.html
Beside that Door(s) not opening and/or closing can be lift, door, or both have problems making module think is jammed and shut off the motor(s).
See my Cave, Gen 2 HL Motor
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
The Ogre's Fiero Cave