ASEA Prod hoist tripped off. Investigation revealed safety limit switch on brakes failed and rope slip switch had bad bearings. Prod. was stopped. Personnel limited to less than 35 until repairs and test runs made. Released to service 9:00 a.m. Shift started 9-6-05 @ 7:00 p.m. Hoist went down 9-7-05 @ 1:30 a.m. - 9:00 a.m.