[Chas]

Some contacts/controls will not be "cleaned" with just De-Oxit... De-grease the socket thoroughly with an oil-less contact cleaner, then follow-up with 91% alcohol (not denatured) dry thoroughly, use a gentle blast of compressed air if available. Find a dud loctal tube, use very coarse sandpaper on the pins of this tube. The extreme roughness of the pins from the coarse sandpaper can be used as a tool to burnish the side of the socket contacts where it is needed most. Gently insert/remove the tube burnishing tool. Some brands of Loctal sockets are fragile especially the spring locking mechanics. At least ten insertions and gentile wiggling about should suffice. Using the same tube-tool apply the de-Oxit as thin film (cotton swab) on the pins reinsert and wiggle to distribute. Remove the tube-tool, then insert the working tube. That should do the trick, if not then replacement of the socket is in order. I don't envy that as it is an RF stage so there will be a plethora of connections...

The control has a flat spot or a grease laden area. It may be possible to repair but there is some risk of ruining the control. Inject that same contact cleaner in the control, back it up with a rag, flood the control and work the control dozens of times, again, compressed air. That may correct it, if not remove the control noting where the noise is by marking shaft position on the body. Take the control apart, and find the spot, if the carbon is completely gone the control is hopeless, if not it may be possible to gently bend the contact arm to an unused area,. Test with the ohmmeter for success. Again, a bit of de-oxit as a film on the carbon will be fine.

If the control is spoiled, Oldradioparts.net will have a NOS one, he is the control guru, Mark Oppat.

Good Luck!

Chas