I have a YM2310. The PTO linkage was stuck when I bought it. The problem was that the shaft that the linkage rotates on had rusted and seized to the linkage. I used penetrating oil and waited. Then more oil. Then I used Vise Grips on the end of the shaft and attempted to rotate it. After several attempts it finally moved. This was after a couple weeks trying. Anyway, after it started to rotate I unscrewed it from the transmission, cleaned it up, added zerk fittings to the linkage and all is well now. It certainly took some patience but it works great now. BTW, after I got everything freed up I found that I kept hitting the PTO lever with my left foot. This would shift the PTO into a higher speed range from the neutral setting of the lever. So I made a block from plastic that fills the leftmost bottom slot of the PTO shifting gate. This prevents me from accidentally engaging the PTO.
Eric