I had a similiar problem last year..when I had reclaimed this unit on maintenance..found when elevator would run fine on multi-floor runs..top to bottom..no problems..but when going on one floor runs.accelleration was so fast 2E circuit was not allowing the proper stopping sequence..which would cause the stepper to go out of step.when car stopped it would not open doors cause it was lost and trap people..the fix was timer to delay the pick of the 2e circuit..this problem never came back and car has been running flawless to date..hope this helps..
