I own a 42" MTD riding mower near a bright deck belt. It still slips. Is in that an adjustment to tighten it?
Answers: no.
Probably just requirements a new belt. I've never see an adjustment.
It should slip while it's not engaged. Other than that you'll obligation to get another belt. Just bear the one you have to the store so they can contest it.
One of the pulleys should have a spring that pulls on the arm to hold on to the belt tight.