thats how we used to do it at work, and I was the lucky one who had to climb in, because every other tech at work is a little overweight
the compressed air and glass cleaner works great, we tried it, nothing. I even checked GM'* SI2000 for bulletins, nothing.
If you look at the right corner of the trunk near the rear window, there'* a seam where the 1/4 panel and trunk meet. inside the trunk, directly below that, is where the water is coming in. It seems the water is getting in between the overlapping panels. We're taking a look at it today, its supposed to rain here.
After this is fixed, the new gas tank and sender, and flex hoses are going in. Speaking of going in, gotta go to the Pontiac funny farm for another fun day.