What replacement grips are available?
Progrip 714s are popular for vibration reduction (grips won’t cure it all, but they can help). To remove old (aftermarket) grips, you may just be able to squirt compressed air under them and “float” them off. To install the new grips, you can use grip glue, or just shoot some hairspray into them and slide them on. Many grips also have circumferential slots for tying down with safety wire.