Edge of the belt will be even with the outer edge of sanding. Using the rear handle to control the Sander and the front. The sand belt and extra pressure will only result in uneven.
Always unplug the sander before doing any adjusting or replacing sanding belts. To change the sanding belt you should loosen the tension adjusting knob until the belt is loose on the rollers. The belt will slide off the rollers and a new belt slides over the rollers.
how to adjust a craftsman belt sander Related Question:
What is the purpose of the tracking adjuster on a belt sander?
Belt sander maintenance Nondirectional belts can be installed either way. The only adjustment you’ll probably have to make is “tracking” to keep the belt centered on the roller. Hold the sander up, turn it on, and see if the belt either rubs against the housing or starts working its way off the rollers.