Definitive method for glass only repair

This question goes for pretty much any iphone, not just the 5.

Has anyone managed to develop a method which leads to having a decent screen after replacing just the glass?

I feel I am close, but am ultimately missing a couple of vital things.

I can successfully remove the broken / cracked glass and all the old adhesive and still be left with a good lcd and digitiser.

What I do next is desolder the backlight from the lcd and replace this with an older already damaged backlight - this is just to make up the correct thickness in order to place the assembly into a jig. I remove the original backlight in order to prevent any of the loca glue from getting in there.

I then use the loca glue and attach a new piece of glass to the lcd. Take it out and clean it up, removing all excess loca glue. I use ipa to clean the back of the lcd panel (although I can never get this looking 100% as it did originally)

Once I'm sure all the loca is removed, I resolder the backlight and secure it back in place. I connect the display back to the phone and hey presto, all is good.

I then fully assemble the phone again, but by the next day, some of the loca has leaked out into the backlight! - and the backlight will sometimes flicker.

No major drama, I can just switch the backlight for a new one again, ensuring that all further traces of loca are cleaned up.... But by now, even if the display looks fine, the backlight still has a flicker. This can't be down to the backlight filter on the phones motherboard as a new display assembly connected to the same phone works perfectly.... So, even though I'm being very careful soldering the backlight back on, am I causing some kind of damage in doing this?

Can anyone see where I'm going wrong? Who routinely does this with good results?

Thank you for reading.