There is only one shaft for the blades to screw on to. I suspect the Shear pin needs to be replaced. Check to see if any pin material is still in the shaft. How? By rotating the blade to where the shear pin is located and if so use a center punch to remove residual material and replace with new shear pin. Snapper1668344
PIN, Shear, .248 ID. X 1.75 LG
(was 7015257) Cost about $5
Reminder remove the spark plug wire so you don't accidently get your hand cut off.
M. Assenza from NJ, April 2013
