Put a new starter on my transit 51 plate 2.0 DI then found the power steering pump is leaking on to it.

Yesterday the starter was stuck only 3 weeks old would this cause it?

 

The fluid from the pump is causing it

 

Nah! Can almost guarantee the starter fault is due to the flywheel. 99% of the time. Yes on these early ones the flywheel is solid but the ring gear is soft. The fact that you have a PAS fluid leak is a coincidence. These vans eat starter motors and I've witnessed people change them time and time again. Pull the box out, replace the clutch and if it has a dual mass flywheel (which it shouldn't have going on the spec) fit a solid conversion. If it has a solid flywheel just replace the ring gear. Available from ford and inexpensive. Once that's done it's as good as new. Fix your leak whilst your in there too. You will need to put a new starter on it too though. Otherwise just keep replacing the starter every other month like most folk.