Part of the repair process includes bushing worn pivot holes. There are 2 popular friction bushing system sizes: KWM and Bergeon. I recommend KWM-sized bushings for all clocks including Big Ben alarm clocks.
Bergeon bushings are a poor choice in most cases, as they require an overly large hole to reamed. This looks bad and it is considered poor workmanship to remove excessive material from the movement plate.
The bushings I like best are “American System” bushings in KWM sizes, available from the major clock suppliers such as R & M Imports.
Example bushing sizes for a Big Ben style 1:
- T3 pivots: Bushing #13, 1.8 mm outside diameter and a 0.9 mm hole. This bushing is slightly longer than the plate, making it obvious that a bushing has been installed. The length can be turned down to match the plate, or you can leave it long to reduce future wear (the pivot is longer than the bushing in either case).
- T4, T5 and pallet pivots: Bushing #05, 1.2 mm outside diameter, 0.6 mm hole. These bushings are almost invisible after installation.
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In regards to Len, it seems like the alarm escapement is worn or broken. The escapement lever is not engaging with the teeth which causes the alarm’s winding spring to fly wide open when the alarm engages. It doesn’t do this outside of when you set the alarm as there is usually a springed tab that engages with the escape wheel that prevents anything at the alarm side from turning. Your options are to remake a new escape lever or wheel or find parts from a donor movement.
I wind alarm up and turn hour hand to time I set (alarm dial) spring totally unwinds, it seems something is not holding. Is there anything an amature like me could do to fix the problem?
Otherwise clock runs and keeps time good. BigBen circa 1935. Thanks. Len