Peter is quite correct with his diagnosis.
This is best sorted with the "bonnet" up! Remove the cartridge out of harms way. Remove the platter. Now lift the bonnet of the deck. Press play while holding the centre "weighing" device down. After a couple of seconds you can release the centre and the sub platter will continue to spin. Now move the arm manually across to where it would be when playing a record. You should be able to reproduce the noise and correct it.
May also be that the platter height is set too low and it is catching on a fixed part of the deck. Platter height should be set/adjusted with the carriage towards the centre rather that in it's normal rest position. As the carriage moves across the record, the additional weight moving towards the centre of the record changes the balance. It's true!!
Let us know what you find.