Keep in mind that sample-to-sample variability in enlarger lenses, particularly with used equipment, is quite high. With any luck your Komuranon-S will be as good as others have said, but if you're dissatisfied, by all means try another lens. Used enlarger lenses are cheap on eBay these days, so it won't cost you a lot to pick up another one, particularly if you're willing to bide your time. If you then decide to continue using the Komuranon-S, you'll at least have a spare, in case you accidentally damage one.