J wrote:

I have a coax laptop power jack that I was able to solder and glue back
together with krazy glue. It broke again. What's the best kind of glue for
the black plastic that these components are made from? Since krazy glue
failed me, I bought some radioshack 'all purpose ashesive'...

Never glue anything without first finding out what kind of plastic it
is, especially since some glues, like krazy glue/super
glue/cyanoacrylate will often stick too poorly to make a strong repair
but too well to be removed and allow a proper repair. If the plastic
is dissolved by lacquer thinner or carburetor spray, it's probalby ABS,
styrene, PVC, or polycarbonate, and it can be repaired by those
solvents or MEK, methylene chloride, or brush-on liquid solvent glue
sold by hobby shops (in a bottle, not a tube). Use scraps of identical
plastic to fill any cracks, and allow 24 hours for the solvent to
evaporate completely. If a solvent repair fails with polycabonate, the
mating surfaces will have to be sanded or scraped to remove the chalky
coating created by the solvent. Plastics that aren't affected by
solvents include polyethylene, polypropylene, nylon, acetal (includes
Derlin) and polyester. Polyester can be repaired very well with krazy
glue or epoxy, but the other plastics need either exotic adhesives
(n-Bond) or have to be melted together with a soldering iron.
Polycarbonate is also repaired well by welding.

You may be able to strengthen any poorly designed part by roughing up
its outer surface and coating it with krazy glue and nylon or rayon.