I've seen pics around of a JVC RC-M70 with several knobs below the tape door. I believe this is called the RC-M75? What are the knob's function?
I can't expand the pics I've found enough to tell...
When I took apart my M70 to replace the belts, this area (below the tape door) in the M70 has plenty of clear space. So, the knobs must have been a design intent from the beginning.


When I took apart my M70 to replace the belts, this area (below the tape door) in the M70 has plenty of clear space. So, the knobs must have been a design intent from the beginning.