hissing noise when turning volume knob?

hi audiogon fellows, recently i have detected noise(like radio tuning) from my right speaker, only when i turn the volume knob. Firstly I'm pretty stupid with machinary stuff, i'm guessing it might be one of fuses is about to get blown out.
I have no idea what causes the problem, strange though the noise stopped for awhile, and then back this week, and there is no problem at all during listening.
I just hope it doesn't die on me anytime soon.
BTW my amp is Plinius 8200mk2 intergrated.
Thanks in advance!!
andy