My record gain knobs make alot of noise need help

I have an old Akai Cassette machine with the nice glass heads. I cleaned the heads and demagnitized them. Everything sounds great accept when I turn up the gain record knob it makes noise fades in and out pops alot statics as the knob increases. Do I spray the knobs, or air blow them. If so any advice would be helpful. I did a
live recording with the machine as is and it turned out really great accept I cannot touch this knob. I leave it at about half way up on the dial. I will be using a TDK MAX-G Type 4 tape on Friday for another live recording of our community orchestra.
Remove the knob and spray contact cleaner. Work the pot back and forth after doing so to help excise the grunge that is causing the noise. You may have to do this several times to get it clean...

Thanks I'll give it a stab.
The best cleaner I know for this application is Caig FaderLube. IME the grunge comes back with other stuff, but not with the Caig.
When you buy an electronic cleaner be certain that it is "zero residue". Some cleaners include a lubricant - this compounds the problem because the lubricant causes more dirt to adhere to the contacts.
Thank you for the great suggestions. I'll post a follow up when I get the Caig.