This is a known issue when recording vinyl. You will never have a 100% correct beatgrid since it is an analog media that can always varies in speed (already in the cutting process). If you really need a perfect Beatgrid you can "warp" the track in Ableton to fix this. But this will reduce the quality of the file a lot. I wouldn't do it.
PLX 500 Recording
i received one of these and when recording my vinyls, the tempo varies up and down, around 0.2-0.3 meaning when i try to assign a beatgrid its all over the place throughout the track, how is the best way to get around this ?