creative adaptation is a requirement for anyone wanting to 'hide' updates to an old rig .... sounds like the addition of a set screw to the knob along with some judicious sleeving [small copper tube?] might do it

Bill


Moved over to the Passing Lane

"When we tug a single thing in nature we find it attached to the rest of the world" John Muir
"When we tug a single thing on an old truck, we find it falls off" me
Some TF series details & TF heater pics & Rust-a-holics Unanimous parking lot