What's happening is as the straw is being pulled through by the roller the engine is dying and I'm having to stop the bed quickly and allow the tractor to recover i.e get rid of the straw that's in the fly wheel and go again. The tractor is all but stalling sometimes it seems like it is definitely going to stall but doesn't quite. Is this likely to be the slip clutch on the way out or an issue with the tractor pto or what? Any ideas please?