I have a sansui 3300 from 1972. It has been mothballed for 35 years now. Everything works which think is amazing! Volume knob static and drops in spots when rotating. Same with balance. I am going to clean all pots and knobs and switches. Before I take the chassis out I would like to know if the pots are hard to get to? Or are there circuit boards etc. which would have to be removed first. Thank you for any replies!!