how to stop a high pitch whistle from a stannah sofia 400 stair lift?

hi james........when i use to service the 400 model we had to also lubricate with grease the pulley wheel bearings top of rail under end cap also the same on the trailing cable trolley weight wheel bearings inside the rail, access by pulling trailing cable out of the top of rail[only grease the bearings] also i used silicone spray on trailing cable.......all this use to eliminate squealing from stair lift rail......if your squealing noise is elsewhere let me know.....paul...portsmouth uk.......

paul
January 2014