Nad c 552 lp stuck on spindle

Hi, so i am currently looking for a used turntable and i found one on a listing. It's a NAD 552 equipped with OM 10 cartridge. It's in mint condition but there's a twist. The top of the platter has been "shimmed" with a layer of bitumen material (car insulation/dynamat) to heighten the platter. Seller told me if he didn't apply the layer plus the slipmat, the LP would get stuck in the spindle due to the platter sitting too low(???) and he did that years ago and didn't know any other fix. He also told me he received a very thick rubber mat with the tt from the store he bought it from as the standar platter "shim" and he quickly replaced the rubber mat because he thought bitumen works wonder for reducing vibration from the motor. From what i found on the Internet, all NAD C552 turntable never have that kind of issue, no shimming required and of course it only comes with felt mat. My question is ; can i return the NAD tt back to it's standard OEM (remove the ugly bitumen layer and put LP without it getting stuck on the spindle) is this because of the subplatter being too high or low? And is it adjustable? I really like the turntable and its fairly cheap, if it's fixable i would certainly buy this from the seller. Thank you and sorry for my english