I finally got my passenger window working (acceptable but not perfect). It still tilts but not enough to come out of the rear weather stripping. I tried widening the front channel - No Go. I tried adjusting the front channel both forward and back - No Go. What worked for me was to add some washers in key locations to force the window guide against the regulator (not sure if I'm using the right terms) - basically the part that slides up & down the center post.

Each of the 6 bolts got 2 washers except the top 2. I could only fit 1 washer between the door panel and the center post there.