All sorted just needed some friendly persuasion from a rubber mallet. Cleaned, new motor and she rotates much smoother and no more difficulties find home position.

I did find this site while looking for some photos of the canon assembly. If you're thinking a shop or playfield swap on a T2 this is very handy.

http://creamyeagle.blogspot.com.au/2014/05/terminator-2-pinball-tear-down.html

Loads of pictures and descriptions