Hey. Ive recent got a Marshall JCM 800 2203 from my late father. Its with a Marshall 1960 Vintage cab. Ive only played on combos, so I have not much experience with this one. Heres to the problem. No matther how I twist and turn the knobs, HI or LOW, I cant get any distortion out of it. Ive searched some youtube reviews on this amp and it sure got alot of crunch to it. Im guessing it needs some sort or repair. Anyone knows what might be wrong with this amp?