I can appreciate that sinking feeling he experienced.
I read a lot before ordering my AEG, and I mean literally all the material that was remotely related to the AA L85A1 here and on Arnie's plus whatever interesting tidbit Google turned up.
The second time I took the front grip apart to take some measurements before ordering a decent battery pack, disaster struck just as I was done putting the handguard back together and passed the sling around my shoulder.
The front sight assembly along with the mock gas tube rod and the whole handguard catastrophically disintegrated !
I took a smoke break after carefully laying the pieces down on a table, got some tools then sat to take a closer look.
I soon identified the culprit, (highlighted in red), a pair of what I initially thought were rivets securing the front sight assembly to the outer barrel.
My first idea was to punch the things back into place with a hammer and a rod but had the wisdom to try some of the most minute screwdrivers I had available first.
After a few unsuccessful tries, it turned out that my smallest torx screwdriver
mated perfectly with what were, in fact, grub screws, the rest was a breeze to put back together.