Plug the saw in to the power supply if it won't start. If the saw starts, but won't come up to speed, check that the extension cord isn't too long. Replace the cord with a shorter one and try the saw again.
Blow sawdust and dirt out of the elevation and tilting mechanisms if the blade won't rise or tilt easily. Debris can block easy movement.
Verify that the saw is mounted properly to the legs, or the work surface, if it vibrates excessively. Tighten all of the mounting hardware and try the cut again.
Adjust the positive stop by checking the blade with a square and then adjusting the positive stop if the 45 degree and 90 degree rip cuts are off. Adjust the miter gauge if the 45 degree and 90 degree crosscuts are out of whack.
Tighten the Craftsman's miter angle knob if the material gets kicked back from the blade, and align the splitter on the blade guard if the lumber binds.