Cassette Hookup
 

If I can bear the sound, I might use the Denon to at least test my hookup for viability.

Soundsmith offers excellent Nakamichi service. It's isn't cheap and - as Ivan noted - they will need the unit on their bench before estimating cost of repair.

Thanks for the information. I’m guessing the cost may be more than I want to spend. I need to decide if it’s a path I want to follow.

Cassette Hookup
 

Is anyone aware of any 3rd party add-on boxes to mimic the tape loop functionality?

What about high quality analog to digital converters? In case I go the other way on recording.

You can't really mimic a tape loop, without a tape loop the next best thing is using headphones on the tape deck to monitor, but that's not exactly the same.

As for an ADC, what's your budget? If I want to go from analog to digital I use a portable Tascam DR-100 which has a nice ADC and I don't need a computer just to record. I've also read good things about Korg's USB DAC/ADC.

Very good ADC’s can get expensive rather quickly. I have/use Burmester.

That's pretty much the way I do it on my open reel tape decks. It's tough to find a dedicated tape loop like in the old days, and McIntosh has totally gone away with it.

Freddie, it's a shame, even the C22 reissue is missing a tape loop but then you've got some brands like Accuphase still including them.

Correct, and it is a feature that I use. ;)