Agree that the cartridge is the most likely culprit but check that the arm moves freely - do this by turning it on with an old record on and once the arm drops, turn the power off at the mains plug. The arm should move completely freely. Also check that you have the tracking weight set properly - it should be 1.5g - or even a little more.
By the way, you have what is a fairly rare gem - these are great music centres. Wonderful amplifier with an excellent radio section - the preset tuning is the best of the mechanical versions - and the Beogram, when working, is based on the 1902 and is one of the best. Where are you based?