I have an old craftsman tractor mower that was reconditioned in the spring. The last time I mowed (a couple of months ago) when I started the motor it was running rough and then died. I found that a bolt (that holds the motor to the frame) was missing. I replaced the bolt but now the engine cranks but won't start... any clues?

Don't know how old , old is , but I would check for spark to the plug , then check and make sure its detting fuel.