dep-5 question

[gscontr]

I have an old roland dep-5 that doesn't seem to get along with my gr-1 synth. When i run them through my mixer (a behringer) the dep-5 clips, and cuts out after a few notes, whatever the input volume. Have tried running the dep clean through the 1/4" jack on the guitar, but get the same problem. My question is, can the dep and the guitar synth be causing some feedback problem through the inputs? Both work fine through amps, but when i plug the 2 in together things go bad.....Could a common bus on the mixer be causing the problem? Also, have a real old re-101 space echo that the capstan hangs up on, any parts available? if not, any pinch rollers compatible? great forum, well informed contributers.....thanks for any help you can offer.