Is the old one fixable? Some epoxy or something? That's an inexpensive route.
As for going LED you may find your lights will blink faster. You'll either have to live with the fast blink rate, install load resistors or an adjustable flasher unit.
Kawasaki Front Turn Signal EX500 EX EX-500 ZR750 ZR 750 ZR-750 ZR-7S Flasher | eBay
if this is right, the ex500's should have a similar indicator. I'm sure it's not the only one. Likely some of the older gpz models too.