Where I've been finishing up a Nakamichi BX-300 cassette deck. I bought two of these on eBay, and pulled the best cosmetic parts off both to make one nice unit.
This one has all the warts and bruises from both units, but works perfectly. I put in new belts and idlers, gave it a complete cleaning and lubrication, and then started going through the Adjustments and Calibration section of the service manual.
And there's a ton of adjustments for each of the three types of tape it can use. "Type I" is good old recording tape. Been around since the 50's, and still works fine. "Type II" are the "Chromium" tapes, which came out in the late 60's. "Type III" are the "Ferrichrome" tapes, which never caught on, and "Type IV" are the "Metal" tapes, and are the height of analog cassette recording.
And they're all buried under the wiring harness. It took about 30 minutes of cutting cable ties and rerouting the cables in the harness just to get this access to them:
These six are for the Record Equalization (aka Frequency Response), and there are six more for the VU Meter Calibration.
Should be a very nice deck when I'm finished with it.
SLW and I have been under the weather with a bug, so that's why the light posting.