I've no idea if the star lock is any good, but regardless you need a good polar alignment before starting guiding, as guiding is most effective to correct for very slight drift and not as a substitute for poor polar alignment. In the latter case, you'd still see field rotation and bloated stars because the guide corrections would need to be regularly large.
IMO, you want to get your polar alignment to a point where you can take unguided shots of a couple of minutes and still get nice round stars before resorting to guiding to help you get longer shots.
As the curse goes, clouds are usually included in the boxes with new kit
