Anyone 3d print?

I got an item 3d printed from a local printer from an STL file I found on t'internet.

It was printed in PA12 but I had to insert a 3mm brass nut into it myself (I used a solder iron to melt/insert the nut)

All was well for about six months but I've noticed that the nut has now come loose - in fact, it's fell out. 

What's the best was to fix this?

It looks like the insert hole is now too big for the nut so I was thinking I could either (a) use a little bit if Sugru to hold the nut in place or (b) glue the brass nut in place.

Alternatively, as the nut is there to accept a screwed in second piece of plastic, I could just glue the two parts together...

So, which is better: Sugru or glue for PA12 & brass? If glue, what type?

Or if I just bypass the nut/screw and just glue both parts together, which glue type works with PA12 and an unknown plastic type.

(These parts aren't subject to loading bearing - well, only about 90 grams - but are subject to vibration and dust/water/sun etc)

THANK YOU FOR YOUR ATTENTION IN THIS MATTER!