My transit is eating starters!

First problem was power steering pump leaking so replaced pump and put another new starter on.

2 weeks later it went again, then i noticed the lad who did the pump didnt tighten up the breather pipe up enough so waste oil had go onto it and ruined another one so fixed that and put ANOTHER starter on.

So that was 2 weeks ago so at a job today turn the key and this starter started spinning!!!!

Started it say 4-5 times after that and been okay but what could it be ruining this startrer? Cant see anymore leaks?

Tempted to sell it and get another as need it for work can't afford to be off the road or breakdown at a job really!!

Any suggestions??