correct procedure to tighten the set screw on the back of the rocker shaft

["Ted S." <cessna@speakeasy.org>]

question: I took my rocker arm off and found that the set screw was
essentially loose, in that it took a turn or two to get it to set on the
shaft, in order to lock it with the top plate, I had to back it off a
quarter turn. Is this the correct procedure ?

also my one of my manuals made a reference to two shims underneath the
center two pedastals. I didn't find any shims in the classical sense of a
shim anywhere.

was this an opps from the PO ?

thanks, Ted Stowe