From my experience: Just recently I might add that I'm waiting for the last reheat of the glue to settle down. This is my first time doing a surface pro 64 1st edition. I replaced the crappy lite-on SSD they so injustly put in this surface, it lasted 14 months. yep, right past warranty. as usual. Heat gun on the screen, GENTLY, low heat, point the tip away from the center of the screen, never stay in the same place more than a second. your arms will get tired. it has to be hot, not searing hot, but not too easy to touch the glass before separation. start at the top corner, go across the top the the other corner. use good spudgy's, I bought a nice set of 5 metal ones from ebay for a few buck, along with a good metal separator with a very fine tip. SLOWLY work the edges, while heating at the same time to keep the warmth up on the surface. NEVER pry on the lower screen. as your separating the top just let the weight of the screen be the separator from the plastic by standing it on end, you will know when its time to do this, the glue will be easier to let it just come off on its own.
On putting it back together, I just made sure the old glue was as even as possible on the screen and plastic. I then slowly heated the glass just going around in circles with low heat for a minute or two. then set it on high heat, 1500 w and quickly went in a circle to really warm it up. too hot to touch. but not melting. I then turned it over on a nice flat surface, glass down, and put about 10 lbs of Stephen King books on top of it to let it help pressurize the sticking process. about 20 minutes later, took off the books, reheated again on low to get a last few possible bubbles out of it, then repeated the Stephen King pressure technique again.
Well, its holding very well, no bouncy of any corners, and all touch seems better than its been since I bought this thing new about 16 months ago. I sure should've upgraded the sd, but I just did a micron 64 in it, next time I will upgrade it.
Oh, by the way. make sure you got a good supply of T2 bits handy. or at least a good set, these screws are murder in this thing.
Patience Grasshopper, and the prize will be yours. Sure beats the price MS wants to fix these things. All tools cost me about 40 bucks with the heat gun. the SSD was 27 bucks used on ebay. I was going to put a 256 in it, I should have, bet I take it apart again before the month is over.