Easy fix. Install the replacement reflector, and dab some some small dots of J.B. Weld around the edges of the reflector to hold it tightly in place. Your replacement reflector, if a re-pop, may not fit tight like the original if you don't. Then replace the metal backing, using dabs of J.B. Weld to hold it in. Sometimes the replacements have to be ground down on the edges a tiny bit to snap in. Use a dremel cut-off wheel to remove rivet heads, if need be.