We have replaced both of the dishwashers at Conch Out within five years. They really get a workout with the renters, lots of overloading and door slamming, etc. We have always purchased Kenmore dishwashers from Sears and it's a good idea to have those maintenance agreements on appliances in rental homes. (We'd never accept one here.) But I would never put an expensive appliance in a rental house...just not appreciated or taken care of.
Sounds like your renters clearly caused this problem and I would charge them at least part of the cost of the repair. Beachrunner, sounds like your management company is not doing their job.
I think the houses are taking a beating this summer, for some reason, and the management companies (including rental, pool service, etc.) are overloaded with accounts so not doing the job as well. Just a sense. I am also sensing that people are demanding more (even if your rents are reasonable) and this was confirmed by our management company. They say there has never been more kvetching from renters than this summer. I hate to say it, but I think some of the newcomers to SoWal are really stretching to rent these places and coming in expecting absolute perfection and luxury. I mean, it's a beach house, folks!