Thefile, I agree with Nandric. The boron pipe can not be replaced with its equal, and any substitute will most likely be inferior.
It might cost more money to retain the original cantilever and have it retipped rather than a rebuild which replaces it. If you wish to retain the original performance, have the same type (as original) stylus as a replacement. This is one area where I would consider an upgrade. If it had an elliptical tip I would consider a line contact or micro, but I'm not familiar with your Supex to make such a recommendation.
Regards,