Ha-ha, no record player has ever been accurate!(big sigh) yes I'm sure. Let's pretend, if you may, that I know what I'm doing ...
Rip was done using headphones, no acoustic feedback is introduced. If the turntable/arm/cart was to blame it would become a constant, hence it would show the same characteristics on every plot I've generated (hundreds upon hundreds of 'em). My system is very accurate!!!
OK it isn't feedback, I was just asking if you were sure...
Having worked in the business years I know quite a lot about record players.
BTW feedback is signal dependant as well as deck dependent so it would be very unlikely to be the same for all measaurements