Rhythmic thumping sound when playing any record

Hello,

I have an old Bang & Olufsen Beogram RX2 and everything sounds great and everything is working fine except for this anoying thumping sound. I have sort of narrowed down the culprit. It only happens when the platter is on top of the sub platter. Its is not audible unless a record is playing, so it be literally be the smallest possible inperfection. This happens with all records. I think the weight of the platter (it is pretty heavy) is making something slightly touch something else.I know that the sub platter nor the platter are rubbing on anything. Also, if you applt the slightest pressure to the record while its playing the thumping ceases.

Are those the three or four screws around the edge? By disengaged you mean unscrewed all the way? They are screwed down.

That fixed it...Thanks!