Maintain belt adjustment as described above.  This drive uses high quality special V-belts.  The V-belts are designed to operate 5,000 to 10,000 hours.  If slipping or belt abrasion becomes evident after operating over 5,000 hours then replace the belt sets.  If after 5,000 hours, excessive adjustments of belt tension are required due to belt stretch, the belts have reached the end of their life and should be replaced with belts as recommended in the V-belt table.  Since V-belts are not widely available, please contact our nearest distributor for replacement.  Belts must always be replaced in matched sets:  i.e., both upper and lower sets must be replaced simultaneously.  Hence, one faulty belt requires the replacement of up to 10 belts.