With only about 40 miles on it, it is hard to imagine much wrong with the secondary (other than a friday or monday build by someone that does not care). If it were me, I'd put the rear on a stand, remove the adjuster screw and jam nut entirely and run it a few times to see if the belt will shift all they way out.
Note: If you have the screw out and everything functions as designed the track will not stop unless you apply the brake or kill the engine. As it will be tight on the drive clutch hub at that point.
If it does, re-install the screw and adjust to the recommended deflection.
If it does not, the issue is inside the secondary.
