Peter, you're 100% correct......but there is a 'statistical' argument that can be made that applies to the likelihood of actually having the kind of catastrophic results you're describing really happen. When one thinks about what 'can' happen, this often includes a good many alternate outcomes. A different scenario is depicted to asking 'what's likely to happen'.....and this is where the probability of catastrophic results is really quite minimal. As mentioned, a good many people have been using the 'DeOxit' product successfully for decades. I dare say it's perhaps one of the best of such products on the market. I'd also mention that virtually any control that would fail as a result of being sprayed out with this stuff was a control that was probably on it's last legs anyway. So, the 'spray-out' was really just proverbial straw that broke the camel's back....but not really the 'cause' of the failure.
I've personally done a fair amount of research on this particular subject. There are a number of products on the market that, with one application, you could literally destroy a perfectly good control. Most of those products state pretty clearly that they should NOT be used for this purpose. So, in reality, this becomes a case of 'mis-application'.... surely not intentional....but still, it's 'tech error'. As you mentioned, the media used for construction of many of these older controls was also quite different from vendor to vendor.....with some being significantly better than others. Personally, I'm somewhat in your camp.....and I believe just some good old compressed air is the best way to start. Particularly when attempting to service a control that in all likelihood cannot be replaced. I've run into this on some old Harman Kardon units....where finding a dual-gang volume control wasn't really too difficult, but finding one with the proper 'loudness tap' was virtually impossible. Fortunately, Mr. Mark Oppat in Michigan was able to 'construct' a new control for me. Mark, as you may know, bought up just about all the NOS controls from about every major vendor.....and now has pretty much cornered the market on providing suitable replacements. He's a great guy and will work with anyone to get the right control for the needed project.
Anyway.....some times the best option is to simply remove the control completely, disassemble it, and 'gently' clean it by hand with soft cloth or microfiber towel or something similar. Even a MILD solution of dish soap in warm water can be a better cleaner for an old grease-fouled control that spraying the hell out of it with a solvent-based aerosol can! And, as long as dried properly, or even 'blown out' with compressed air, this can be a better and more effective method to preserve what you've got! Just don't go spraying soapy water all over the place!........lol. Finally, it's also important to GENTLY lubricate the shaft in the ferrule after all this is done.....and wipe away any excess material. DO NOT apply so much as to wick back into the control itself. Generally a drop off the end of a pin is enough!
So..... beware of what the spray cans say.....and 'yes'...they can dissolve both the backing plate material, and the conductive media applied to it. But, if you are going to use a spray, then something designed specifically for such controls.....like DeOxit..... is probably not going to result in a problem. Just spray it in, work it a few times, then blow it out and don't let it 'sit' on the control surface for too long.
Hope this helps!!
Tom D.
