If your 2x72 belt starts taking more passes to do the same work, stop the grinder and inspect the belt. Material packed between the grains can block the cut. A worn belt can also cut slowly because its abrasive has dulled. The remedy depends on what you find.
Look for material sitting on top of the grit
Wood dust, resin, or other debris can pack into the spaces between the grains. Look for patches that resemble the material you were sanding. On compatible belts with dry wood dust or light buildup, a rubber belt eraser can help expose the grain again. Follow the cleaner and grinder instructions. If the buildup stays put or the belt still rubs after cleaning, change belts and check that the abrasive suits the material.
Compare the cut with a fresh belt
A dull belt can look fairly clean. If it takes extra pressure to make it cut, leaves an uneven pattern, or heats the part faster than it used to, try a fresh belt of the same grit on scrap with the same setup. A fresh belt that cuts cleanly under the same conditions is a good sign the old one is spent. A cleaner can lift debris. It cannot restore dull grain.
Pull damaged belts from service
If you see a split edge, torn backing, or a lifting splice, replace the belt. If both the old and new belts cut poorly, check your grit choice, workpiece support, and speed against the grinder and belt makers’ instructions. When refining a blade, let the scratch pattern tell you when to switch grits. The 2x72 grit progression guide shows what to look for.