dont think its the score reel because;

1. score reel moves freely if i do it manually
2. this is a replacement score reel that Daniel was kind enough to send me! The problem was there with the original score reel as well as with this new one 

OK .. had forgotten about that .. I did start to re read the whole thread but took the lazy way out .

You sure there isn't a closed 100pt switch on the playfield ? I've been caught out with that problem before .. though if that were the case, when you 1st start a game the 100's reel would advance one position and the coil would stay locked on