the starter clutch has a wick in them to keep them lubed, when they start to
scream it means they are no longer lubricated / became rusty / have some
type of dirt in them. to clean them you want to clean up the shaft part of
the crankshaft that goes inside them with a fine emery cloth, you will also
have to clean the inside of the clutch where the shaft fits into. lube it
up. this does not always work and you are only left with replacing the
clutch. as for the tabs on the shroud they come with 4 use only 2 at a time
and when 3 have broken off it is replace it or have someone weld tabs back
on

hope that answers your questions.