Definitely worth getting a MityVac. I have used mine a ton over the past few years, definitly worth the money I paid for it. And it will save you a bundle in mehcanics time. The door lock system is pretty easy to diagnose. You can test each door seperatly without pulling the door panels and see if it is leaking vac. Then you know which panels need to be removed. I guessing you have a actuator that is leaking.

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