Quite easy to do actually...start warm engine up and back off front locknut and gently screw in centre bolt until any noise disappears, then back off quarter of a turn....sorted ( Not that anybody else but moi is interested ! )
Some Kawasaki’s had a semi auto adjuster. Loosen it with engine off and retighten. I’d have expected to need the crank at a particular position but not on the old 400/750