Well, I went back to the MX-5 with my test tape & made a slight speed adjustment to both decks. They were running around 2980Hz, after tuning by ear vs the reference 3000Hz. Now, they are at 2996-3002Hz for deck 1 & 2998-3003Hz for deck 2 & here's a demo afterwards, featuring some Bee Gees tracks...
Enjoy: