Strong adhesive for hard plastic?

It almost entirely depends on the plastic and you may find it rather difficult to identify unless it has one of those pointy triangle plastic type markers.

If it's polythene or polypropylene then it's difficult to stick, you need glue specifically for the plastic and it requires the surfaces to be 'prepared' with something that treats the surface so the glue sticks (that's chemically 'prepared' not just roughened).

If you're lucky and it's polystyrene, PVC or ABS then you can stick it with standard plastic pipe cement or any old 'hard plastic' glue. This will 'solvent weld' it and give a good strong joint.

John Towill formulated the question :

Assuming it is the lampholder at the end which has broken, you used to be able to buy replacements. You just need the name of the manufacturer of the fitting.

Fluorescent end fittings seem to be made from some highly filled plastic formulated to take the temperature, which then embrittle and fracture. Not easy to repair. Epoxy is good because you can bulk up the thickness.

Which pieces exactly, have broken off? Brian

Yes if these bits are the only damage and the rest is not into crumbling territory, then araldite, not the rapid the normal stuff, and maybe mixed with some powdered glass fibre dust? My guess, though is that the whole thing is now very brittle and likely springing it about to put another tube in will mean sooner rather than later, a nasty failure of one end or the other. Brian

I would guess at the two hooks, which latch into the metal spine of the fitting.

correct. Sadly it is Chinese, so finding the manufacturer will be difficult if not impossible. Ifd only I was a sailor I could use this Chinese junk!

There is probably nothing that can repair that sort of embrittled plastic and provide the strength it needs to be a retaining clip. Your least worst option is probably to reassemble and glue it together with epoxy. Accepting that next time around it is scrap.

One way to fix such things is to add 2 hose clips to hold the tube, then the connectors only need to push on to the tube. A cable tie is another option, cruder but is less visible.

NT