How do I replace the primer bulb on my lawnboy silver series self propelled mower? I purchased one but cannot seem to figure out how to replace it.

You must remove the engine cover (three torx screws) then you can pull the line off the plastic bulb disk and remove it from the cover by pushing the side clips.
Put silicone on the bulb disk and force the bulb on to the disk. I had to use a vice to hold the disk, it is a very tight fit. When you get the bulb on the disk, reinstall it in the engine cover and reattach the hoses. The gas tank hose will probably need to be pushed on to the carberator and the gas tank also. This is hard work but is the only way you can instal the bulb.