SWR Redhead grounding problem

Question

Hello,I have difficulties with the grounding of my Redhead, it gives a hum through the speakers, when i start to pull and push the k***s for bass, treble and balance on the amp, it stops after having push and pulled them several times. I have cleaned the pots, but without long lasting success.Do i need do get new pots or is there something else wish causes these grounding problems and what brand of pots are put in an SWR ?Please e-mail me at , thanksJack