Adding to what Peter said, RF alignment must be very precise in order to secure precise results. Some radios are impossible to get tracking perfectly across the dial. If you have lots of time to waste, you can compensate on the problematic part of the dial by bending the outermost condenser rotor plates (tuning condenser). Then compensate elsewhere with the normal oscillator/antenna trimmer adjustments (depending on what section you're tampering with). Unless you have much experience (and even then), this may prove to be more trouble than it's worth. I don't really recommend it at all.
Good IF alignment is a key factor in station tracking accuracy, though.
Thomas