OMNI-D tuning knob problem

[Jim Janke]

My old OMNI-D has a problem when I turn the tuning knob 
counter-clockwise (down frequency).  At one recurring place in the 
rotation the frequency moves back up 200-400 Hz when I take my hand 
off the knob.  It is not a hand capacitance problem, as I can actually 
see the knob move slightly and it only happens at one spot in the 
rotation of the knob.

Anybody ever have this problem?

73,
Jim K9WIE
Lakeland, MN