I have rebuilt @ 6 eunits not hard to do separating them .. cleaned each one with scotch pads etc etc.. The old fashion way
Today I got another switcher that was left in the basement or garage worked but needed cleaned
This time I thought I would try something different I had a bottle of BRASSO liquid cleaner polisher. So I soaked the bottom in a small container (not the coil) then I used a small stiff paint brush and dabbed it around the drum etc.
After I let it set fro a minute or two I rinsed it off with hot tap water .. WOW this thing shined and cleaned not only the brass drum but the fingers looked shiny NEW after a hair dryer ..I tested it WORKS perfect every time.
Worked for me , ..........DAniel