From the "For What Its Worth" department;  When I replaced the clutch slave cylinder I found the bleed nipple to have a longer grip length than the one it replaced.  The result was a sloppy fit where the spring attachment tab fit against the body of the cylinder casting and less tension on the clutch lever return spring.  A couple of thick washers fixed the problem.  I know that some may use a substitute spring with less tension or don't use one at all, but is my understanding that a strong return spring will reduce premature wear of the bearing by keeping it from constant contact with the clutch diaphragm.