So when I upgraded my speakers to JBL L150s I noticed my right channel had slightly less gain than the left. I swapped everything around and finally narrowed it down to the preamp after swapping in a Marantz 3200 from the garage system. Tore the 2000 apart last weekend and ordered parts and also finding a broken solder pad. I've had this unit for probably 30 years, getting it I think from a pawn shop outside Ft. Bragg NC. Five years ago I recapped it, but it really needed a total rebuild. So I started this morning, all new or NOS silicon, all new caps, and all new 1% resistors. And I had some of the good wire left over from amp builds so why not use it. I'm thinking I'll get it finished and back in the system tomorrow. And yes, rebuilt it wearing a Magnivisor for magnification and checked components against the service manual through out rebuild and after. Many of the resistors were of slightly different values than the schematic and like resistors varied quite a bit from each other, debatable if replacing them will make a audible difference, but i don't want to go back into the unit in the future. And, I'm sticking with the stock opamps.