Another option: If you still have the broken-off piece....
Clean the mating surfaces and epoxy it back on. Use tape to "clamp" it in place until the epoxy dries. Clean any squeeze out with the epoxy's recommended cleaner/solvent. Contact cement would probably work, also.
Do a dry fit before committing to any gluing type fix.... meaning clean the mating surfaces of any debris, to make sure of a good seamless fit.