ok thanks all, I was going to clean it thoroughly but since
electrolytics can leak I thought experienced users might see signs of
leakage if not cleaned,
I was also hoping it might be the switch, but after checking with
ohmmeter it works ok.

err, what exactly is esr meter?
My voltmeter can check capacitance (but I need to desloder them and put
in special place for checking probably because of cable capacitance,
right?) and it can see if capacitors are shorted.

I can check resistance between various points, if that could be of any
help for solving the problem?