Hello all, my name is Ledge I am the proud owner of a Harman Kardon 75+ that has served me well many years purchased new in 1973. I have been using it with the Right back and the front left. The front left just gave up too with pops and noises. I replaced all the Electrolytic caps on the amp modules with nichicon muse, Qty-3 47uf and qty-2 220uf caps. hoping that would repair my problem, it did not. I do have the schematic and was hoping somebody could please chime in. i read the MV on the speaker terminals i read RF+ 73.2, LF= 88.5 and raises up, LR + 35.5. RR= 3.0 1.5 7.1 highest this channel works great. My left front has alot of pops and static. Can anybody please give me some insight on this and what I should do next. Are there any known problems or parts on the amp boards that I could check out. Thank you for any advise. Regards Ledge