https://lookup3.toro.com/partdex/index.cfm?xCaller=Toro&lang=uk_en I would visually inspect, hands on, everything associated with your transmission linkage, looking for worn or loose parts. If everything checks out ok I would lube all moving parts with oil squirt gun making sure not to get oil on belts. Next I would adjust clutch per your manual page GB29. Let us know if this helps or not.