When we had trucks in an aluminium foundry, we didn't differentiate between them and any other customer with regards 'damage' and 'normal wear and tear'. If the seat got worn, or the mast hanger bushes wore out, we fixed them, but if some idiot driver took it to close to the fire or poured molten metal over it, that was damage and they got charged. We got one back that took an apprentice two days with a hammer and cold chisel just to get the metal out of the mast,another with all the wiring and dash in one molten lump, no way are we covering that.