You need more info. What car is sticking people, what floor is it happening at, how are the people getting out, is it running high speed then stopping, stalling in leveling, is it sticking right when the doors close, is it leveling into the floor then not opening the door? You need to talk to the folks who are getting trapped to get more data. Gotta put your detective hat on with those old units. Definitely will need a full set of prints. Call up the old timer who took care of it for 20 years and see if he has any ideas or a full set of the prints. You might need to sit on this one for a few days to figure it out.