I am looking at a late 70's JMP combo. The guy says "no mods", but it has new tubes, grill cloth, logo and Celestion Heritage speakers. Would those "mods" hurt the value at all? I'm guessing not much, but wanted to hear your guys' opinions first. I had a 70's JMP head in the late 80's I loved (but sold in 1989) and now have a DSL 40 with Celestion 12M-65 (which I really like). Since the guy lives 80 miles from me, I would like to hear your opinions on the combo. I'm just looking for another amp with that 70's vibe to keep upstairs. Thanks for your help!