Marantz 10b repair

Bruce,
Can you tell us where you found the optocouplers and how much you paid for them? These would be easy to repair or replace with CDS light-dependent resistors (LDRs) and NE2 neon bulbs. The trick is knowing the specs of the specific CDS resistors used (dark resistance and illuminated resistance). I haven't come across this info for the 10B on the web yet. Surely someone knows or could measure a known-good original 10B optocoupler. Once that is known, CDS resistors are relatively cheap and easy to find.

Yeah, I'd be curious about opto-coupler spec as well.

I always made up the opto couplers under the assumption I would never find the originals. Seems to me most of the time the neon bulb has failed and you can re-use the LDR. I wonder if that HiFiBruce ever got his sorted tuner out? Sounds like the discriminator was out of alignment.