I bought this from the original owner. I have the owners manual and I'm selling the GFA-535 amp he had in a separate listing. When I fully tested this unit everything worked for a while and then suddenly the sound would go low or quit all together. Wiggling the volume seemed to help but not always. The volume would come back and everything would be good for a few minutes until it did it again. I am no expert so I don't have a clue as to what is really wrong here. when it was working 100% every switch and input was tested and found to be working properly. Other than some dust and a few scratches it is in excellent shape especially the faceplate and rear panel. Buyer to pay actual shipping costs. Please ask any questions before bidding as there are no returns. Sold for parts.