Hi,
I just bought a R13, and it just came in (so HAPPY!!!! sound so much better than B12)
I played around it for a bit than tried playing my scales,
strangely my transition in the A (and D, F and any other scale that needs to use the C# key with the left hand) major scale from middle A to B to C#
is either squeaky or not coming out.
I can play my scales perfectly fine with the B12 and is suspecting that it may
be defective key work. Any opinions?

Thanks!

I think you're talking about 3rd-space C#, and if so, then the problem is only a minor adjustment. Sometimes pads and/or cork will "settle" on new horns and become slightly out of adjustment and cause that key to leak. You wouldn't want to adjust it yourself, so let a smart clarinet teacher or repair guy do it for you, just to be safe. Congratulations on your new horn!

Does a Band Teacher that plays the trumpet count as a
"Smart Clarinet Guy"
And recently I noticed, the longer I played, the smaller
the problem occurs.