Welcome to DC Ph86 someone here on the site should have an answer for you. Might take a while, the site has been kinda slow lately but someone will chime in. Everyone else has a life, I on the other hand am recuperating from knee replacement and keep checking in out of boredom.
I have never heard of them being repairable. You can drill a small hole (1/8" of so) at the end of the crack to keep it from cracking more then fill it with super glue. Best bet is to find a good used one