Regularly old appliances are offered who need to be restored. The question is, of course, is it still worth to effort. Just as a TOA 100V amplifier.
This amp, from a customer, has already experienced what. Recently by a fall, was quite the front print ripped and recently he worked almost no more. There came a little sound from with a lot of failure.
Upon closer examination turned out to be 3 potentiometers piece. One was broken, another result of the previous fall, but two others that were worn by use. Not, however, immediately on the way you would expect, namely a worn carbon course.
Here you see that is cut the connections of the resistance path to the terminals. This is due to the construction of the axis of the runner. Time goes by, you get this injury.
This might be solved by using glue with silver in it. Only this glue is quite expensive.
Fortunately, there is still a potentiometer with the same shape and dimensions and for sale for an acceptable price.