The leak could be caused by a problem with the rinse dispenser or by a worn out corner seal. If the seal looks bad, dried out, etc., replace the seal. Otherwise, you'll need to take the door apart and see what's going on there.
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Right side corner seal
- Breakdown diagrams for
Model DU430-20
Just so you know, this Jenn Air dishwasher was made by GE. A basic GE dishwasher with Hotpoint brand on the front will usually cost about $180-$200. But, if you do decide to get a new dishwasher, I strongly recommend going with a different brand like Whirlpool or KitchenAid - it's more expensive, but you get what you pay for.
I can't really advise on a repair contract. No idea what the details of it are.