In the USA there are 2 or maybe even 3 in Minnesota at Drive-A-Tank, and also one more runner in New Zealand at Christchurch, used to be a tank driving adventure, ex-Vietnam vet.
Malcolm, have you counted the links in the track? I know there is an acceptable wear guide which allows for the removal of a link, maybe 2-3, can't remember the exact number. I remember a fellow in Australia who had removed too many links and the track was tight as a piano wire, eventually he ended up tearing off the idler or the final drive.
When we got ours it was new track but loose and it wanted to jump the sprockets...no fun tightening Centurion track without the proper ratchet tool!
Christchurch