I have an Amati Kraslice serial 403766 clarinet in Bb. It plays well so far as I can tell even though it's 15 or so years old. How does this clarinet rate in your opinion?

What model is your clarinet ? Amati is the company that makes it, and Graslice is the town where the company is situated. We need to know the model to give an opinion.

I think the number must be ACL 201. That's the only other number on it

Yes, ACL201 is the model. It is a student grade instrument meant for beginners. I suggest you Google "Amati ACL201 Bb student clarinet". You will find lots of information including users reviews. I have one and I find it just as good as the American Vito (by LeBlanc) and the Bundy (by Selmer). Good luck.

Thank you. I will do what you say.