Another thought...
It could also be the top floor safety limit plate that is bolted to the right rail is too low. Now, if the elevator was working correctly before, this is probably not the case. But, if that safety limit plate was found to be loose and maybe slid down an inch, now the safety limits would engage when the elevator comes to the top floor. The top plate on the right side rail needs to be just high enough to not trip the limit switches when the cab is empty and account for any minor bouncing when entering and exiting the cab.
