Your correct. I probably should not have posted after screwing up a nice 4G LTE screen at the very end of an hour plus of fiddling. Anyway as you say doing it by hand is (just barely) possible but its too time intensive for me *I'm running a microbiz. I dug around some more and found a you tube video titled "How to separate the screen from glass using SM-252 separator" In short its an adjustable hotplate so you can insure you don't cook the lcd. Then you use a Molybdenum Wire (Like a garrot) to slice the glass (Or Digitizer) off in one clean cut. To get all the glop (glue) off the Display you can use a chemical called LOCA or LPA and an ordinary toothbrush. They have a glue to rebond the LCD to the Glass (or Digitizer) *Note you need a Ultra Violet light sounce to cure the glue. They sell UV flashlights on Ebay and probably a number of other places.
One design issue with the 4G is that laying it LCD side up rests the camera glass down and thus you get scratches which make the image worse and worse. There are some ways to polish scratches out of glass *Like the LCD! I cleaned up a few scratched camera glass using tiny dabs of toothpaste and an old electric toothbrush followed by rubbing with papertowel etc. The 4G is still a great phone.
I have a small home biz repairing HTC phones. Buying Digitizers from Ebay has not been too bad but it does happen once in a while. I'm talking maybe 2% I would say that its rather amazing that any work what with how some are shipped. *No padding. I just found this site and am glad there are other people who hate throwing away great stuff like the HTC phones. BTW That gap where you get 1/4 of screwieness is how I see these fail. Don't give up. *Or if you do send me the broken phone! I'm always looking for more of these to fix.