have you made any adjustments on your handle bars? I put new bars on my Grizz couple years ago and got the brake lever mount to close to something or other and it wouldn't let the assemble release all the way.
I posted this for someone else so not sure if he did or not I will ask him .
As for the size I think it's a 420 ? Sound right
? I'm a Honda guy so not 100% sure but I do know it's a 400 something lol .