I have a Craftsman Lawn Tractor that recently started jerking in several of the gears. Took it to an equipment repair shop, they said it was the transaxle and would need to be replaced. Couldn't afford for them to replace it so I did it myself. Everything went back together just fine, but the tractor does not operate any better and even will not shift into all the gears. Are there any linkage issues or other adjustments to the shifting that I may need to be looking for?