I purchased a rx c100 boom box and I notice when I play a tape the left is louder then the right side the left sounds like it a little distorted and when I record it sounds the same way radio plays fine cleaned the tape heads and also demagantized it as well its almost like the gain is to high on the circuit board

Could be that someone has messed with a potentiometer on the main board for PB GAIN LEFT, or that 'pot' has got issues, might need some contact cleaner sprayed on it, or rotated back and forth a few times.

Assuming of course the Panny has such a pot, many boxes do.