I have read several posts regarding power steering leaks at top of steering shaft on this model tractor. This leak on my tractor is not continuous but is getting to be more often and my power steering becomes almost like manual steering. I pulled the steering wheel and the rubber/metal bushing has some really worn areas on bottom of rubber portion. Also, is the shaft other posters mention as having a groove worn in it at the top of the shaft just under the steering wheel? This shaft on my tractor does not have such a groove or show any significant wear. Would someone please offer your experience with this issue?