All warranty repairs are at the sole discretion of Panasonic and there is no mention of transferability -
YEA or NAY, so that's good
With a turntable from an overseas maker I'd be surprised if there was due to the nature of the beast though, but they don't print it so you may be good (legally)
I have read the warranty carefully and the dealer does NOT have the authority to transfer or even tell you that a warranty transfer is possible - see above
These are the times when dealing directly with an established dealer (who has some leverage and latitude with bending the 'rules' and making things happen, face to face, pays off and makes a good argument for brick and mortar but I digress and is beside the point at hand
On the positive side there is NO mention of the dreaded "original purchaser" limitations but you do need that receipt with a date and purchase amount - that they make clear
The warranty also suggests that if you cannot obtain satisfactory results to write them at the address provided
That's what I'd do and quit wasting your time with flaky dealers (that will often overstep with words just to get you out of their hair, regardless of brand)
Here's a copy of the manual (and warranty) if you don't already have it
Good luck
https://www.technics.com/support/downloads/data/operating-instructions/SL-1200G_PPS_TQBM0005.pdf
I also think that if the seller was on the up and up and a square deal kind of a guy he'd get his dealer to resolve this for you - but one way or the other you're probably going to have to be shipping this table to some place anyway - so at this juncture I'd just deal with Panasonic from this point forward and save what would most likely be a redundant mailing
The seller should also/also have, provided you with the receipt - why would/should you have to chase it down? That's the most concerning part of this growing story
Afterthought:
Did you try re-seating the platter as I suggested? Clean the platter bore and spindle with an optical grade cloth dampened with isopropyl alcohol, and or, a shed free electrical paper wipe the same, apply a THIN film of oil to the spindle with clean fingers and try that
I'm repeating myself now but I have cured this very same issue by doing said same