Madfly
+1y
I always went thru a couple of steps before applying the glue and material. There was at one time available TSP or trisodium phoshate. This did an excellent job of removing the "armor all" type products as well as dirt, oil, and plastisizers which may have leached out of the plastic. It is still available in a more environmentally safer product at Lowes. Anyway, clean the pieces with a good detergent like Tide, and rinse well. Let dry and scuff with the scotchbrite. Wipe it down with Acysol or SEM plastic prep and use a good hi-temp spray adhesive like Dap/Weldwood.