Levinson 326S Volume Knob Loose

agbrace OP: Nice!

@ellajeanelle Thanks, the plumber's teflon tape was a great idea. A single strip around the brass drum allowed the knob to slide on smooth without too much force and holds it perfectly.

agbrace OP: I know what you mean.  I like to fix things properly myself. Maybe the spring-loaded bearing is seized?  Lubricate? There is always epoxy (but permanent) or while plumber's tape.  Better option than electrical tape.

Personally, I would see if the entire pod is available and I would install a new one.  Can't be much more difficult than some patience, some screws, desoldering and soldering.

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. 
 

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.