Fairlight-CMI

Does anybody ahve any idea on what can be used to replace the tip in the pen on teh 
sereis lll alpha keyboard?

It's is almost imposibel to use this pen now as the tip is so worn. Used to be able to 
keep the pen at a certain angle and would be able to deal with the quirkiness but 
that's not working anymore. It jumps all over the place now. 

Really need to find a replacement tip for this. 

Any ideas?

Jerry