I own a Sears Craftsman 22" 6.5 HP Self-Propelled Push Mower (Model #917375520) that will not start. I noticed that the circular metal contact inside the spark plug boot was pushed below where the spark plug would normally snap in. I pulled the round metal clip forward and snapped the boot onto the plug, yet the mower will not start after several attempts over two days.

Any suggestion would be greatly appreciated. Thanks for your help!

Hi,
Off the bat I would spray some lightweight lub in the cap, wiggle it to distribute and slide it off the wire. I would think that from the description that you possibly do not have a connection of the terminal to the lead any longer.
Peace,
Clarke

I would just add that old gas and clogged air filter can cuse this problem if the spark connection doesn't solve the problem.

Lets check for spark on the get go. Pull plug and put plug wire back on plug. Ground plug to head and see if there is spark there. If not pull spark plug boot back and check for coil wire connection to the metal round clip. Also see if there is corrosion inside that metal clip for a bad contact. Just because it feels clipped back on doesn't mean it is. Use your finger to on the center of the boot top to make sure it is actually clipping onto the spark plug tip

If this metal clip was pushed to far and loose on plug that clip needs to be lightly pinched with pliers to clip/snap onto plug tip

The only next thing for spark would be a bad coil