Levinson 326S Volume Knob Loose

I just purchased a used 326S preamp and noticed that the knobs for input select and volume are loose and can be easily pulled off. It was cold when it was delivered so I thought when it warmed up it would be better which it did help a little bit, input select is now snug, but the volume knob is still pretty loose enough to slip on the main axle. I also noticed that the brass axle drum is shallower for the volume than for the input select, is this normal? 

Anyone else experience this?


Have you considered changing the knobs with ones that have a set screw?

Is the head of the shaft designed with a slit?  If so, you may be able to spread it out carefully to a larger diameter so that the knobs fit tighter.

There is a brass drum attached to the main shaft and a spring loaded ball bearing that should apply pressure to the inside of the knob so maybe it has just lost its rebound but wonder how to fix. I suppose could put some electrical tape on the inside of the knob to make up for the difference but don’t like cobbled solutions.