Macintosh MX132

Need help/thoughts on an older Mcintosh MX132 preamp. The unit has issues in which I only get a loud buzzing noise when I try to play music through the unit. I use it only for 2 channel. So I have the front outputs running to the inputs of my amp then my music server outputs into the cd I put of the MX132. Again all I get is a loud buzzing noise. Try doing the same set up in zone B of the MX132 as well but get no sound at all from zone B. Funny thing is if I run the cables from my amp to the fixed outputs of the MX132 it plays fine but no volume control...

is is the unit worth fixing? I got the unit for free... If the unit isn't worth fixing my budget is about $700.00 to find another preamp. Thoughts and help on if I may have the unit set up wrong? If I could get zone B set up properly then my issue would be fixed.