Just changed some Otis belts on a 2000Kg Gen2, all went well. returned to service and tested to all floors was just about to leave and filling out log card when we noticed the lift had moved slightly.
On looking further we found that the belts are creeping over the sheave and the lift is slowly moving up, seems a lot when you look at the video but in relation to car its about 10mm every 15mins.
Checked tensions and all springs are within 1mm, belts are original manufacturer, no changes have been made to affect the balance, there is no coating on the belts that requires removing or cleaning and its purely slip no drum/sheave movement.
Any ideas appreciated, posted a video here Otis Gen2 New Belt Slip