I'm having trouble with some decks at the moment.

They were skipping a bit, so I thought they would benefit from calibrating.

Downloaded a guide to it, and all has been fine until I get to the bit where you zero the tone arm and then dial up a weight.

I zero the tone arm, so that it floats... but then when I try to dial up a weight of 3g (which is the recommended weight for my carts - Ortofon Concorde DJ S) I find I can't actually go any higher than around 2.4, it gets stuck.

Anyone got any idea where I'm going stupidly wrong?