Audio Systems: blown reciever?, real vintage, performance equipment

Question
I have an old Nakamichi tuner/amplifier model TA2A. It is probably late 80's vintage. In the last few months the volume on one speaker is modulating up and down. The other speaker seems to be constant. The amp has A & B channels on the speaker out put and have tried running the speakers on both channels with the same result. The speakers are ADS L810's bought used, and at least initially they gave me no problems. Do you think I have an tuner/amp problem or a speaker issue? Also given the vintage and quality, is it worth pursuing repair, or is it time to move on and update my system?

Answer
The only real vintage in stereo equipment is performance equipment. By that I mean $10,000 plus amplifiers and the like. Even that stuff is as expensive to service if it fails as it was to buy. Manufacturers do not generally keep an inventory on parts older than 5 years. There are companies that do but they're looking for suckers who are willing to pay top dollar to repair something not worth repairing. From that you should be able to draw your own conclusion. The quick and easy way of testing your speakers is note the speaker going up and down. Connect the speakers to the amplifier in reverse. If the speaker that was acting strange when it was connected to the right channel, does the same on the left then there is a problem with that speaker. If the varying volume remains on one channel, then the problem is either the speaker cable or the amplifier.