Hammering is OK, within reason, don't pound on it with a big sledge! Just keep the hammer blows off the outer ring! I use a big 3/4" drive socket, and tap the balancer on with a 3-lb. drilling hammer. This keeps the hammer blows centered on the hub. The danger is in dislodging the outer ring, which is rubber-mounted. If there's a center bolt hole, some parts stores have a threaded installer that bolts to the crank center, and a big nut is turned to press the balancer on. If yours has a tapped hole, it's been added by someone after it left the factory!
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!