I have a Kenmore Ultra dishwasher and the thermal fuse has blown twice in the last few weeks. I replaced the door switch as it wasn't working properly, but within a week or so, another blown fuse.
Each time the dishwasher fails there is a significant amount of water in the base, so it appears to be failing repeatedly at the same point in the cycle.
Any suggestions on how to pinpoint the faulty component?

You may have a failing pump and/or a thermostat sticking. Are you getting any error codes?