Unfortunately @GHNelson I don't think the issue is fixed. The bubble count has slowed this morning and I've just had increase it. It's definitely not dropping as it did before but it's not staying at the same rate. It's very strange as yesterday the needle valve seemed to be very sensitive after adjusting the working pressure and today it's not. Or maybe I've imagined that! I've found a bottle of gas leak spray and literally sprayed everything and can't see any leaks but if I listen closely there is a very tiny hissing noise coming from around the solenoid. It may of course have been there when it was fine. Is there anything else I can try at this point? Thank you!