ab.1.6. Zero Set Dial Mechanism and Pulley
It may be found that the rear washer of the zero set pulley has broken off and it is no
longer possible to move the plastic window with the dial cursor. The pulley consists of a
front washer, spacer, and rear washer. Originally, the shaft holding the rear washer was
peened to hold the washer in place.
If the washer has come off, but is still available, it may be possible to reattach it by
replacing the spacer and pulley on the shaft and soldering the washer to the end of the
shaft, or dimpling the end of the shaft using a center punch. If soldering, be sure to
clean and tin both the end of the shaft and washer before soldering.
If the spacer has been lost, it may be possible to replace it with one salvaged from a
rotary switch.
If the rear washer is missing is may be possible to replace it with a brass washer of
about the same size (1/8” hole, 0.375” diameter, and 0.012” thick) and solder it to the
end of the shaft.
If the zero set mechanism is intact, but the operation is erratic due to slippage of the
pulley, it may be possible to improve the operation by cleaning the pulley with a q-tip
moistened in alcohol. If this is ineffective, you might try using a thin coating of a ‘non-
slip’ liquid to the inside of the pulley.
Zero Set (part 2)
If the "zero set" dial window (with the vertical line) is "floppy", the clip holding it to the
tuning dial hub has probably come off (the clip is available at hardware stores). If the the
"zero set" dial slips, the pinch roller, made up of two spring washers, is loose. It could
be just wear over time but the problem I've seen here is that someone pulled the front
bezel/panel off, not knowing that the pinch wheel is supposed to stay with the dial.
As the aluminum shaft oxidizes and increases in size, it tends to stick in the plastic
bezel (easy mistake to make - personal experience). This stresses the rear spring disk
and bends it and/or pops it off the shaft.
To fix, flatten the spring disk if necessary. Place a nut on the shaft, against the front
shoulder to distribute the force, and insert the shaft loosely into a vice, small socket,
hole in a metal plate, etc. Put the rear spring disk on and make sure it's flat against the
shoulder on the rear of the shaft. Center punch the shaft to expand it slightly and hold
the rear spring washer. It would also be prudent to find out where the old part(s) went if
anything is missing.
Servicing Procedures Page 76
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