sounds familiar from my old work van a 03 reg diesel tranit , evan a fully charged batt would intermitantly fail to start ,stick the jumpers on from a running engin it would start , this eventualy dident work , a new startermotor was needed , turns out it had 4 starters in 6 years, crap... clutch dust and muck contaminate the electrical innards, there is no way to prevent this. there is evan a sticker on all transit replacement starters saying - warenty void if found to be contaminated with clutch wear dust. -- sorry loose the ford its a no win game.
lee jcb mecanic, July 2010