moves around a centimetre or two
do you mean mm or two?
That isn't nice how they have done that, you are going to have to try a hard plastics adhesive to start with and clamp it for a few days while it sets.
Maybe you can bond some thin tin plate (soup tin) under the whole part once you have glued it back.
I would try and make the whole part in steel but that is me 
Free speech is expensive these days!
Sorry to see those pic Nate.
I think bonding the disc back on is a definite good start and then either use a shorter screw or use washers to effectively shorten the distance that the screw travels in to the thread might be worth a try?
Either that or drill a hole in the bottom or the gear box to allow the screw to travel further in by a few mm.
That way the screw wont push against the bottom of the gearbox and force the disc back out.
Hope you can get this sorted 
AGM MP40 - AGM STG44 - CYMA Thompson M1A1 - WE P08 4 inch - Marushin M1 Carbine GBB - AGM Sten MkII
Hmm... which gave me an idea.
Perhaps actually get a slightly longer screw and screw into the gearbox? If not then shortening the screw should be easy enough.
That, combined with some sheet metal expoy-resin glued to both sides of the plastic bit as a strengther will help. I've used some bits from the casing of a broken PC power supply for stuff like that in the past. Some tin-snips make it easy to cut.
How about gluing it all to the gearbox? It maybe hard to remove again though!
You could try just gluing the bit that's come away from the gearbox to it... or maybe drill some holes and screw it on with some countersunk screws? i.e. attach it to the gearbox rather than the other plastic bits.
What about if the holes were here:
Edit, if anybody knows of anywhere that could manufacture this part from steel/alloy/aluminium or anything other than bloody plastic please let me know.
We would need more photos of the whole unit to be made.
I am starting to think I did quite a good job on my home made one now 
Free speech is expensive these days!
Good pics.
Not a hard thing to make in steel I don't think.
The only hard part is the tube part in the stepped area, maybe it could be turned down to slide into a smaller hole then pushed in and then riveted over (expand with a ball pane hammer to hold it in place).
Welding that tube in would not be so easy.
Free speech is expensive these days!
Just looked at the linked pictures, that piece looks well abused what is the criss cross scoring all over the out side surface. Just been looking at mine and trying to work out how that could get broken. It must of had at some point a gorilla trying to tighten it up, the wood work must be caved in as well. Do you have the spacer that goes between the damaged part and the stock,is that damaged as well, the selector plate/arm also sits in this bit. This could be a reason for the disc popping out as when assembled the gearbox, damaged part, barrel/hinge assemble, spacer and stock are flush/tight together. If you need pic's I'll try and get some up later.
Armoury: AGM MP40, AGM Sten MkII, K98K/vsr and Maruzen P38.
Is the spacer missing as he said?
Free speech is expensive these days!
How did you bodge it?
I would bodge it with sheet tin plate from a soup tin as it is thin and fold it all the way round the channel shape and bend it over the edges at the top also bond it on. That could be a good safe way to mod these so the don't break.
Free speech is expensive these days!
Good news mate 
, glad you got that sorted, may I suggest, if it holds and having a new piece made proves to difficult just leave it as you've done and drill the extra holes in to the gear box as Yith suggested, this piece would then just act as another spacer and not have any load on it.
Ian
Armoury: AGM MP40, AGM Sten MkII, K98K/vsr and Maruzen P38.
