[Red Raster]

These dials are prone to spilting as what has happend to mine on both the Dumont and the StrombergCarlson. I would guess that center collar is the culprit. On both sets i found that it was unnessesary to remove the dial and did not to avoid the risk of more damage, As with my sets you may find that
end part of the shaft where the knob is secured may be rough thus requiring extra force to get indicator discs off.
I had no problem lubing the gears and restoring the chasis, If it has to come
off be gentle.

P/s show us pictures of the set with the restored cabinet, nice clean chasis.