2nd hand cassette deck......

if you buy budget casette decks when they were generally new they usually have solenoid operated switches which click , with cams they silent, and also with the naks the wow and flutter figure is less than comparitive models.

Nakamichi  tend to use their own tape mechanisms, motors, designed inhouse, and they also make oem kits for others, did i also mention better shielding as well less hum .

I got that bit, but my interpretation of what you wrote was that the different head-block mechanisms (cams vs solenoids) contributed to a deck's SN ratio, which is why I was a bit lost