Your Yamaha YCR 2330 II should serve you well and I'm glad that it's polished up nicely. Oil the valves and put grease on the slides and it will be fine (Vaseline will do but special slide grease is better). You might like to check what mouthpiece you are using as some suit learners better than others. I'm not a Cornet player so can't really suggest what might be best for you but others might if you ask. If you haven't already done so then you might also like to consider cleaning it out with a snake and some water, there are posts on cleaning-out instruments. I appreciate how intimidating the process of contacting a band can be and what your expectations of your own competence might be. As a band member and someone who's always interested in potential new players my own wish is to hear from people regardless of ability, IMHO it's the desire to learn that is most important and the building of ability to allow that to happen is a joint process. Take courage, pick the phone up and talk to people, then arrange to visit a band of two without your instrument just to get a feel for things - IMHO you can learn a lot about a lot by just sitting in on a rehearsal as an observer. Any good band will listen to you (initially that's talk not play) and see what ways forward there are, IMHO they'd like to hear from you sooner rather than latter because that helps them too. Good luck and I look forward to hearing how things turn out for you.