Realignment, the correct term, is required periodically on ALL analoge and to a lesser extent, digital tuners. An analoge tuner has several RF,(Radio frequncy), and IF (Intermediate frequency) stages that all need to "Track" each other to properly tune in the desired station. The alignment proceedure is outlined in the maufacturer's service manual for each tuner model. The technician should be using a precision FM RF signal generator, Multiplex generator, Oscilloscope, etc. to optimise sensativity, selectivity, and distortion. Typically they will not fiddle with the dial string unless the pointer does not move to the proper locations at the dial extremes as noted in the service manual. Other adjustments are usually specified to set the dial pointer to the correct frequency. The time period between alignments depends on the environment the tuner was used in and the quality of the parts used and design of the tuner. A proper alignment can take several hours if nothing is broken! A digital tuner (frequncy synthisized) may only have a couple of adjustments relating to distortion that can be made but it can still require an alignment periodically. I hope this helps to clear up any misconceptions.
Doug
Doug