My uncle just gave my son a g-100 amp. it is a old tube amp made by yamaha . it has a lot of scratchy niose. the amp works. someone said it might need to be cleaned. do you think that will work?. if so what do you clean it with?

The g-100 is a solid state amp produced by Yamaha in the late 1970s.  If the "scratchy noise" is produced when turning the knobs, it can be cleaned by using a spray called "de-ox it" or an electronic contact cleaner and lubricant like CRC-56.  The best way to clean old rotary potentiometers (the electronic part of the knobs) is a good hard turning.  Moving the knob back and forth with firm gentle pressure can actually clean off residue and result in a cleaner tone.  Try to apply the cleaning spray to the knob stem only and to no other surfaces.  Another great electronics cleaner/spray is Contact ReNu made by MillerStephenson. If the problem persists you might want to take this amp to a pro repair guy. Good Luck!