technics 1200 problem with pitch once warmed up - TECHIES - FILL YER BOOTS :)

yo peeps - any help or guidance appreciated.
I have a problem once one of my decks warms up.
after a few minutes it goes mental if the pitch is moved from 0.

in a minus direction it is fastest near to zero, then slows lightly towards -8

In a positive direction it seems constantly fast.

I suspect this is associated with d301 or associated circuitry, but if anyone has any experience of this issue, your input would be welcome

https://www.facebook.com/video.php?v=10206083176579716&pnref=story

soldering irons warming up siman . . only goes like this after it's warmed up so component related me thinks . .

cheers for your input