Matt,
I am not very familiar with Liability Law, but it seems that if you mess with it, then you could be absolving Ssnake Oyl of their liability if the belt assemblies fail due to mechanical reasons.
Best piece of advice I would offer you would be to let them fix it for you. You have already paid them the price for the repair, so "bite the bullet" (in reduced driving time) and make them repair it at no cost to you. The last thing one would want to happen is to tinker with the mechanism and have it fail when you most need it.
My wife drives our Vette on occasions, and I didn't want to risk the seat belt failing while she drove it. :eek..so I waited for the repair, and luckily, I have not had any problems.