Any chance someone changed the stationary and movable contacts prior to this trouble starting? Otis used two types of materials for their stationary contacts. Could someone have replaced the metallized (copper) stationary contacts with carbon contacts? Like a voltage drop, switching to a carbon contact would create a drop in current.
Check and see that the carbons are even and the copper paddles have plenty of wipe.
Is this a 2 of 3 phase unit?
