As it turns out, getting the kinked drain tube replaced didn't solve the problem. After the next big heavy rain, the driver's footwell was soaked as much as ever. So I thought maybe the windshield had developed a leak (it's windshield no. 3 because of instances of rock damage on the highway). I took the car to Binswanger for a leak check. The windshield was fine, but they found a lot of debris under the cowling and cleaned it all out. They said it was a common cause of leaks and didn't charge me a penny. Since the Binswanger fix, there hadn't been a heavy rain until last night. We got 3 inches in about 6 hours. This morning the footwell was dry as a bone. Finally, problem solved!