Or maybe put on an other thumb strap first?
I never liked the original thumb strap on the 114. My thumb gad a hard time as well; I guess that is normal.
So a accordion builder (Karel van der Leeuw) put a free pivoting thumb strap on mine, and that worked fine.
Because a 114 is very light, you don't get much stability playing standing up, but of course you can always attach a shoulder strap. I have one, but hardly ever used it.
My strap looks like this:
see http://www.youtube.com/watch?v=uN0aqdjvq6E

I mean my thumb strap of course.