Simon... Is the connector for the pull in wire an eyelet(round connector) or a blade connector?? If it is the blade connector,Ford had corrision problems with these.I can't remember when Ford switched from a blade to an eyelet.The blade connector can be cleaned or replaced.This was just another idea for the starter problems.

99 SE Sport..ATX
SVT exhaust
SVT zip tube and air cleaner assembly
Tinted windows
17" Cougar Zn Wheels