Afternoon all, pertaining to the subject line what is the best type of glue for effecting minor repairs on a running model? In this instance we're talking the (non-working) coupler end of a DMU which has fallen off.

Depends on the material and whether it's a painted or plastic surface?

For plastics I prefer to use thin liquid solvents which flow into the joint by capillary action - apply just the tiniest amount to the joint (after fitting the part in place) with a very fine paintbrush. For example, Humbrol Liquid Poly.  If the part has a peg which protruded to the bodyshell then apply the solvent from the back rather than the front.

I also keep a plastic "bottle" of thicker liquid glue with a long fine spout for when it's easier to apply a tiny drop of glue to the peg or hole before fitting the piece.  For example, Humbrol Precision Poly Cement.

For metals or waxy plastics then I use superglue, applied from the end of a pin.

(NB, I don't necessarily always use Humbrol products, there are plenty of other brands offering the same sort of stuff!)

I have used a product called GS Hypo for some repairs. Its used for jewelry repairs and I used it a lot for repairs to clear plastics as it dries clear. It has a precision applicator integral to the tube. Its a bit like super glue but not as instant. I have never had a problem with it and used it extensively.
The other product I like is Deluxe Glue 'N' Glaze. It seems to stick to everything, dries clear, and is not an instant stick.

Thanks chaps