

The gauge manufacturer indicated the end-plate is needed for belts wider than 1-1/8-inch.  I've always re-installed the 
end-plate screw into the barrel (see pic) although this time I'll find a thick matching rubber washer to fill the gap.

Also, the HMC website indicates their single-barrel "AWI - I" drive belt gauge is good up to 1" wide belts, and verbally 
confirmed 1-1/8" belts too.  But wider belts need a wider gauge.  Ref: http://www.hmc-international.com/awiwb170.htm