You need to remove the wheel adjuster from the mower deck. There are spring clips and a washer on the inside holding them in place. You'll have to take the right wheel side off first so you can drop the transmission down far enough to get at them on the left wheel side. Once they are out, you can place the adjuster in a bench vise to hold it and the busing can be driven out. I used a deep 7/16" socket. The new bushing can be pressed in place by opening the jaws of the vice wide enough to get the bushing and adjuster in, line the bushing up with the opening in the adjuster and turn the vise closed. There's also a dust seal on the inside of the adjuster. They are numbers 11 and 14 on this diagram.