I decided to investigate my 197 today. I found that it is not worth trying unless you are replacing the control.
No way to use a spray contact cleaner or anything for that matter.
They use a cheap but sealed control. The thing is a dual control with the power switch mounted on the rear of the control.
It is held together with small rivets so no way to get any cleaner inside as it also has sealed leads on all sections.
It is not marked with any manufacturer markings either but it is the same blue color that Bournes uses on some of their controls. It must be the economy line if they did make it as they usually offer well made controls.
I guess the only way to repair would be to replace the control and hope the new one is better quality. Something tells me the new one will also go noisy in a year or less though so I'm just going to live with it.
The volume pot is the middle chamber so no way to work any contact cleaner into it even by hoping it will run down the shaft.
I'd cut the rivets if I had something to use in their place but they are small diameter and I had nothing here that could have been used to hold the assembly together again.
I think I will order a spare control or two in case mine becomes worse.
That is only if they sell the control without the small board it is mounted on otherwise they would likely ask an arm and a leg for the entire control and jack board as an assembly.
The RadioShack service manual for the 197 does not list a RS part number so I assume it must come from GRE. They list three different part numbers for the same control and who knows what the difference is. Maybe one is a newer version of the control that solves this noise problem. The numbers they list for the same control are:
RG82BS-2A1-B103-0EC2 or GE-03D-0200 or GR-08D-1220.
Has anyone ever ordered a board level component or mechanical part from GRE before?
Maybe Doug will know if he sees this.
The Radio Shack service manual for the Pro-106 and 197 both show they use the same exact control in both radios, just the knobs are different. The service manual has no Radio Shack part numbers (RSU numbers) for any of the parts at all so I have no idea if a company owned store can order the parts or not from the numbers as they are listed in the manuals.
I have a couple good managers here in town that know what they are doing so I may call one of them and ask unless Doug chimes in with an answer. One of the guys I know well has been a store manager for at least 40 years. I met him when I was a young teenager and he is still a local store manager to this day. He has switched stores a few times though. He must be getting close to retirement.