How can I keep my display glass from falling off?

I have a MacBook Pro Mid-2009 Unibody (A1286, MacBookPro5,3). I've successfully done a number of repairs (several DVD drives, hard drive upgrades, memory, etc), but this last one has me stumped.

About a year ago, the display glass started to come off. It's held on by a ring of what is basically high-quality double-face tape. My guess as to the cause is that I use it about 8 hours/day in Firewire Target Drive Mode, and it gets pretty hot. Either way, the tape fails, and the glass comes right off, leaving the LCD and aluminum frame exposed.

Since then, I can't get it to stay on. I've replaced the tape twice (two different vendors) and the entire glass once (from Ebay, with presumably Apple-supplied tape). I've cleaned surfaces with alcohol. I've heated the tape, put the display under pressure (the Complete Far Side is just the right size) and left it overnight. I now keep a sheet of foam sandwiched between the display and the body in Firewire Target Drive Mode to keep the heat down. But, no matter what I do, in a couple of weeks or months it comes right back off.

I'm almost to the point of running a bead of silicone around it to hold the darn thing on, the heck with the appearance, but opted to post here in case anyone had any suggestions.

... Any ideas?

Thanks.