@cmnparlance, several folks on here have given you good advice, mine came after a look at the schematic as I'm sure others did as well. For the few dollars it would take to replace the parts why not just do it! If the problem remains than we can look at other more unlikely causes.
From your post it's pretty clear that you have no technical or service experience while people who DO have experience you seem to question and ignore. I would hate to be your auto mechanic.
BillWojo
@BillWojo, First of all, thank you for all the advice you’ve given me along the way.
I don’t think I’ve ignored anyone who has given me concrete ideas—in fact, I feel like I’ve gone out of my way to respond to people on this thread, follow up on their suggestions, etc. Way more people than I ever expected chimed in, so I couldn’t respond to everyone of course. And as for questioning people, I’ve perhaps asked for clarification or confirmation, but I don’t think I’ve unreasonably doubted anyone’s knowledge or expertise. I simply want to know as much as possible, before I put any more work into this, whether a particular option is likely to make a difference or not.
In the case of this switch, I’ve been told by someone else that it’s unlikely to make a difference, and so I’m trying to suss that out before I spend any more time and money going down this particular path. You yourself previously said "if [the speed variance] is random, replace the switch" which I took to mean "if it's NOT random, the switch probably isn't the problem"--and it's not random. Perhaps I read too much into that? Of course changing the pots as well, as VintageDutch has suggested, may be a different story--and I realize that's not mutually exclusive with anything that you've said.
What's funny is that I was all set to buy the JVC-recommended switch (because you had told me that it was probably a specific form factor or specs), but it went out of stock and is apparently never coming back. So then I had to research whether another switch would work, since the other ones I could find online look different--would they fit? What did the numbers on them correspond to? I don't have the background with this stuff to be able to answer these questions myself, and it takes time to get the answers either on here or through other internet research. And then people say differing things (and sometimes contradict themselves even), or use jargon that I'm not familiar with.
The fact of the matter is that although replacing the switch and pots may seem like a quick and easy job to many of you guys, it’s daunting and I’m sure will take me considerable time. I’ve spent many, many hours troubleshooting old audio equipment over the past year, and it’s been more frustrating and time consuming than fun, to be honest. I do enjoy aspects of it, but I often feel like I'm grasping around in the dark and even with all the wonderful internet resources out there these, I sometimes come away feeling more confused than when I started!
Hearing from both of you that replacing the switch and the pots is the next relatively easy fix that may make a difference, I am now leaning back towards doing it. Let me try to find the parts and I'll get back in touch with you guys to confirm that I am ordering the right ones. It may take me a while to get everything sorted out.
Thanks again.
