Might be worth lifting the platter and checking the lubrication. Some turntable bearings have been known to seize when too much is present. On the flipside the oil supply can dry up completely?
Please remind me : are the AS turntables the ones that have a bearing lining/sleeve "moulded" to precisely fit the bearing??
I remember reading one initial review of such an arrangement showed a tendency to seizure i.e. indicating that the bearing was slightly too snug or that even temperature may have had an effect, but I could be wrong?