@lewm
It appears the cantilever carriage is universal across most of the Astatic/Glanz range, but each model has a variation in cantilever material and/or tip.. So if you have 2 assemblies that require a new cantilever, and they cannot be repaired, you might be able to find a worn out Astatic/Glanz cartridge with the correct cantilever ( doesn't have to be the same model ) and replace the tip.
So what I am saying is grab a donor Astatic/Glanz ( doesn't have to be a MF2500 ) with an aluminium cantilever in good nick and try it in your MF2500 - retip if necessary.
My feeling is that given the position of the cantilever is more critical than most MI/MM cartridges to achieve the constant flux as per the Glanz patents, rebulding may be difficult to get right. If you can start with a good factory cantilever assembly you would be more assured of keeping the overall integrity of the design..