HI, I HAVE A 4-TRACK CASSETTE PORTASTUDIO. I'M RECORDING THE BASS ON TRACK 1. THE LEVEL LIGHTS ARE RESPONDING CORRECTLY AND I CAN HEAR THE BASS. HOWEVER, WHEN I PLAY IT BACK IT IS BARLEY AUDIBLE, UNUSABLE. I MAINTAIN THE DECK WELL. DOES ANYONE HAVE CLUE AS TO WHAT THE PROBLEM MAY BE? THANKS.