plastic dials on Heathkit SB301 and other models

[K8DI]

Admin/Mods, please move if it should be moved...

I have a SB301/401 pair, that I got off eBay about 30 years ago. After alignment and minor repairs, the receiver saw infrequent use, but always seemed to work ok.  So, a while back, the dial one day would only go one direction. Something let go. It is currently all the way to the top of its range and stuck there. I don't want to force it back as it is all old fragile plastic...

I have not had it apart yet. I am wondering if anyone has experience with, or a reference or web link on how to fix these mechanisms.

Ed

[w7fox]

Almost every one of these I've seen has a crack at the 15 kc line.  Probably the crack is hanging up on the 100 kc follower pin.
 
The failure is caused by pressure from the pinch wheel drive cracking the plastic.  I have glued these using solvent plastic cement, but first the pressure from the pinch wheel needs to be relieved so the plastic can be aligned.  After the glue is dry, the pinch wheel can be tightened GENTLY!

You may have to dress the spiral threads where glue may have dribbled out, with a modeling knife and jeweler's files.