Thanks mate - yeah, that centre gear's a bitch.
The counter gear can be changed for the CRP brass item. Various 1.0 pinions are available on eBay.
Centre gear? The guy from Time Tunnel 'melted' his original gear so he had some ground from polyoxymethylene/POM/delrin/acetal (whatever you want to call it). I was thinking that bonding two delrin 1.0 module gears together would work (or you could use a 1 module 12T gear and bond a larger 32 pitch, or 48 pitch gear to it)
After a fair amount of internet searches I found these:
http://www.smallparts.com.au/store/item/gs100120900b0600achp/gearsspurmodule1/
http://www.smallparts.com.au/store/item/gs100240900b0600achp/gearsspurmodule1/
http://www.smallparts.com.au/store/item/gs100180900b0600achp/gearsspurmodule1/
There are other pitch gears on that site too.
Apparently delrin's quite hard to bond, but this CA glue claims to bond it well:
http://www.dymax.com/products/cyanoacrylates/pacer_cyanoacrylates/index.php
I think that reinforcing it by micro-drilling through both gears and inserting wire 'pins' should work quite well.
For now I'll use my 20T/12T centre gear (and the 22T/12T one that's on it's way from the UK) but I'll try the above method if it looks like I'm starting to trash them!