I've owned a B6200 for about 3 years. Usually I warm the glow plugs for 10-15 secs, and it fires up in about 5 secs (I live in NC). It never fails. We went overseas for over a month and I inadvertently left the tractor uncovered. When I came back I worried if I'd face starting problems. Sure enough: it took maybe 30-45 seconds to fire up, sputtering all the way. I thought that after the first start the rest would be like start ups before I left it uncovered, but now it struggles on every start. I have Diesel Klean in the diesel. Any suggestions? Thanks.