Just got a job with 13 Otis gearless cars modded with O'Thompson Ultraflite gear. One car has trapped five passengers with the fault "limit board tripped."

This does not happen at terminal floors (lobby and 40), or even within a few floors of the terminals. It also has not happened at the same floor twice. I understand that the limit boards are no longer made, have to be sent out for repair. I have checked locks and gate switch, figuring that I might be clipping or bouncing a lock. The last entrapment was in the dead zone.

I have yet to see it fail, other mechanics have just reset the fault and let the car rip. I read that there are three diagnostic LEDs on the board. There is another car out in the rise for repair, are limit boards interchangeable within the group, or do I need to do a learn trip? I am going to babysit the car tomorrow, anything else I should look at?