Interior light stays on & Door Ajar light on

I've been having this intermittant problem where the interior light stays on as well as the Door Ajar indicator. My rear wiper doesn't work either when this happens.
So I got this bright idea of spraying all the door latches with WD-40 and it seems to correct things, temporarily. But not the rear wiper. And now the driver side rear window has decided to stop working.

Do you think I should take the Windstar to a dealer or is there something I can do to correct this?

There are 7 door sensors in the Windstar. I have no idea where they are located, but last spring the dealer replaced five of them. Now the problem has returned, intermittently, but eventually the interior light will just stay on, draining the battery when parked. You can pull the fuse but the power windows will quit working along with the light. Seems to be a common problem.

The sensors for the front 2 doors and the sliding doors are average run of the mill pushbutton switchs operating the same as they have as long as I can remember (60s models had em). The hatch uses a different type and they are usually the problematic ones. Basically you will need to remove the interior door panel and unscew a couple of bolts to gain access to the switches. Do a search in this forum. the step-by-step instructions were posted about a month ago.