Dunno 'bout "uneven" wear, but all of the trannies that I've had
shuddering problems with have at least had WORN (out) yoke arms.

Those arms start out life as rounded surfaces (hill-like) over which the
throw-out bearing gently rolls into position, but as they age, they wear
down to flat (plateau-like) surfaces, which, when engaging the clutch,
tend to violently rock up and down till the clutch is fully engaged.

Since replacing all of my yokes, I have had no problems with a
shuddering clutch.

Prior to replacing those yokes, I replaced: engine mounts, transmission
mounts, TO bearings, clutch slave cylinders, friction plates and have
had flywheels resurfaced, all at the advice of supposedly helpful
list-members.  None of these helped a bit, but new yokes did the trick.

BTW, John & Al, you're both right.  Oil on the friction surfaces of the
clutch will develop hot spots where the steel of the flywheel is
crystallized and becomes very "grabby", but a bad main oil seal will
almost never get oil on those friction surfaces unless it is really
spewing out (not likely).

Karl Wolz