I posted earlier about how the '94 Caravan ES I'd just bought came with no spare tire, and the butterfly-shaped piece was missing from the end of the cable on the carrier.
Upon going to the salvage yard I discovered many of them to be similarly broken. I don't know if rust played much of a part in that or not. The frayed cable ends that remained didn't seem to have a lot of rust on them.
But I can see how it would be VERY easy to overtighten it and put _many times_ the stress on that piece than it should have, i.e. hundreds of pounds versus merely the weight of the spare tire.
I finally found one with cable intact and installed it, and I think the only way to operate it with minimal chance of breakage is to raise (crank) the spare tire up until it just contacts the floor pan, and NO MORE.
Otherwise, it's no wonder they're all breaking and dropping the spare, which could be a potential disaster if it hit someone, which has probably happened.
Anyway, just a FYI to mention to your guys in the shop.