It's the most time consuming and meticulous repair on these machines. Is it hard, I had never touched a transmission before in anything, and I went through it during a rebuild on the crank, and got it back together and still running, that was over 2 years ago. Pictures mean 1000 words in this case as all the parts in the tranny have a front and rear side as well as similar looking parts on both shafts. You have to split the cases obviously, so in my opinion getting the motor out and back in is the hard part. I have good shop manual pictures I've clipped I can send you. Without them I'd still be scratching my head. Zip lock baggies and a permanent marker are your friends if this is something you are going to attempt. Hope this helps. PM me for the pic's if needed.
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