Crackle

There is static/crackle coming out of left speaker even when the session on pause. It started about 3 weeks ago.

I've an old Sansui 221 which had been crackling with the volume control. I cleaned all the knobs that were causing crackle successfully, they all seem very smooth now. However yesterday before I did this I was using it and after about an hour noticed a developing hum. After another 30 min it...

I've an old Sansui 221 which crackles when I turn the volume control. and some small points where the sound can almost cut out. I've been researching how to fix it and it looks like a contact cleaner would do the job (I only need it for short term use). Should I get something like Servisol Aero...