How to replace a drive belt: a practical owner’s guide. Need to do a drive belt replacement? The secret to a belt that lasts is not the belt itself—it’s the condition of the tensioner and pulleys. Worn supporting parts will destroy a new belt quickly. Order of work: confirm routing, release tension, remove old belt, inspect pulleys and bearings, match the new belt, install, set tension, and recheck after startup. Common mistakes: skipping routing verification, replacing just the belt, wrong size, contamination, and incorrect tension. Check the whole system before you start. Check tracking after startup. Get it right, and the job stays done.