Just got your second post.... see my first post on testing the motor head...
there is not enough current through the wiper lead (microamps into the op
amp) to blow away any oxidation or crud....hook up the resistors as described
and rotate the beam back and forth several times and then rehook up the
control cable... very likely you will be back in business...
If that hadn't worked on mine I was going to hook a variable power supply
across the wiper and one end of the pot, and start with low current, 10 or 20
mils, and rotate it back and forth to cook off the oxidation, retesting and
increasing the current sequentially, until it worked, or fried.......
Denny
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