Yep I have with my upgraded 2000 WC-1. It's a pretty common problem. I bought the belt tentioner kit from Whizzer. I am even using it with my auto clutch and it works great.
Whizzer Motorbike
It is pricey but it solved my belt issues. The only other way you can get around the problem is to find a 28.5 inch belt. The AX-27 is a 29 inch belt. The shorter belt will pull the pulley down farther and then the belt will clear the mounting posts.
Good luck.
Jim
PS This picture is from a very respected Whizzer expert. Quenton Guenther. Thanks Lee