When Dinosaurs roamed the Earth they were made from Mobay plastic and I have one that is from 20 years ago that is just like new the base is what needs repair. I normally drill both ends of a crack. The Permetex will not hold up long term it is not made for UV exposure I do not believe. Epoxy it sane it than paint over it. Be careful with dielectric grease it can get in the way of rf ground and the signal propagation. I used to wax mine a few times a year. I figured the oils and distillates in the wax would keep the plastic in good shape and wax and UV protection helped it as well.