If the parts are styrene - how about glueing it with lacquer thiner, then after it dries well, a little sanding, then repaint - that should do it IMO. If the parts were resin or else, I'd take CA glue instead. In such case, I'd still moisten the mating surfaces with lacquer thinner - CA tends to work beter then. Good luck with the fix, have a nice day
Paweł