My apologies. Did not read your post correctly.
I would follow the lever linkage down to the case. I wonder if there’s a place in need of some penetrating oil and lubrication. While doing so, look to see if anything has been bent, damaged, etc.
My recollection with the smaller machines is the lever turns a shaft that goes into the case.
You may have to pull the left rear wheel to get at it well.
Have you used the PTO before?