Although it is supposed to accurately replicate the real thing, the fidelity of simulators does vary from excellent to bloody awful. Even the same simulator can drift off calibration over time.
So, if you don't always get it on the centreline don't let that put you off. In simulated IMC you probably won't be so aware of discrepancies between input and result but it may become noticeable when visual and may get worse the closer to the ground you get. This is not to say you shouldn't strive for accuracy. Just avoid over-controlling to compensate.
A good sim instructor will recognise your technique and decision-making for what it is and make allowances for the machine.
If you are really struggling and the sim instructor does not allow any slack, invite him to demonstrate. If he can do it, given some practice you should eventually be able to do it too. If he can't or is not prepared to demonstrate, there is something wrong.
Last edited by Mach E Avelli; 23rd Jun 2013 at 23:19.