"anything that sat so long unused probably will need some caps"

Oh quite probable. but if you intend to change every cap with marginally high ESR you are chasing your tail. The fact is that some are more critical than others. What's more the more ripple or delta current applied to each decreases it's lifespan. I a a pro and I will tell you now, DO NOT just change all the damn caps. It is a waste of time. You need to find the ones causing the problem. If you want to replace caps to restore original performance find the ones in the audio path and **** all the rest, unless they cause a problemm. There are exception, like in the PS. You take them on a case by case basis. If you just change all of them that don't read like new you will have succeeded in wasting a bunch of tie and money.

So, in kooking for caps, find the muting line and everything that feeds it. It will have a feed from the servo for whenever it is switching speeds. It will have lines from both video and AFM detectors. If the video detects a loss of V sync, out goes the sound. any variance in signal level more than about 30 % at any time will trigger the muting.

There are capacitors used in the muting, if they go open what happens ? It will always be muted.

Did you get a print for the unit ? If you can't I have one person I can call maybe. Maybe. If you do have a PDF of it send it to me and I can probably localize the problem to some extent.