I don't have a spare of that particular plastic, but something I'm going to do in the future (soon) is replace the metal caps and washers with plastic/rubber variations. More flexibility under stress, shock transfer, etc. I have read that doing that is decent insurance against cracks, or minimizing/ending further damage.

I don't have many spare plastic parts at all for this game, and they are virtually impossible to come by. You may be able to service that in some fashion, that will stop the cracking. One good thing about those outer plastics is that you don't have to worry about ball contact. Not much anyway.

One possibility would be to take them to a glass shop, and get them shaped and cut to new form, using Lexan. Then it would be a matter of getting a good scan and possibly going the water slide decal route. Lexan is nice because you can drill it, shape it with a grinder/sandpaper, etc.