How far down the splined shaft of the regulator is the handle supposed to go? There's a beveled area on the shaft, is this where the allen head locks the handle into place or does it just hold it against the splines?

 

You should slide the handle on until it just touches the quarter trim panel.

 

I think there is also supposed to be a nylon washer between the handle and the quarter panel trim. I have them on my car.

Since we are talking about the rear window handles, I'm curious of something. Why is it that it has a set screw on the side instead of being done like the front ones with the allen screw from the front? The reason I ask is that my rear ones do not stay tight and about every few months one of the rear ones is loose. Occassionally one will fall off.

 

I would use a tad of locktite on those. I do work on currency counters and they love to use set screws for all the rollers. Over time they come loose, but throw a tad bit of locktite in there and they don't come out and a year down the road, although stiff, aren't impossible to get out when a roller needs replaced.

 

I had thought about that, but was worried it might pose a problem.