sonab 85s turntable

[deecee10]

I have been given this turntable and am not familiar with it. I think I have a problem with the tonearm mechanism. Even before I put on the counterweight or the headshell, the tonearm does not appear to have balance. it is heavy at the rear. Is there meant to be a balancing weight at the front of the base of the tonearm stand (beneath the surface of the tt)? There is a plastic lip about 1cm long with a groove in it but nothing attached.