The axle on my SunJoe lawn mower would frequently pop out of it's groove and change height. Installing this lock, the axle becomes fixed in place. You will need a screw and a nut to attach the lock to the frame. The photos show how the lock is attached to the frame.
Because of high ambient temperatures in Texas, I opted to print this in PETG. PLA would probably also work.
The author marked this model as their own original creation.