A little rotation isn't a bad thing. rocking side to side isn't good, as it can result in the rotor hitting the cap terminals inside. Tighten the spring clips a little by bending them with a pair of needle nose pliers. Make sure the cap is fitting all the way down onto the distributor housing- - - -sometimes the counterbore at the base of the cap needs to be scraped a little so it can slip over the housing correctly.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!