Shoot it, and find it if there's anything you don't like. If there is, look for something to fix it.
I shot a '10 for a couple of seasons, and found nothing needed doing! I stuck on an invert nightstick barrel, which seems to just work for me on any marker, and a POPs ASA, which is just nice and convenient. You might drop £40 on a cure 4 bolt but, other than a good service and getting it set up nicely, there's little to improve.