First, I'd think if I had messed with any wires before the signals started messing up. Reason being my indicator is normally on when the signals themselves blink off. Reason being, current flows from the main switch to the indicator and flasher (called turn signal relay in the manual), which are in parallel, then to the turn signal switch, then to the turn signals. When the switch in the flasher is open, the current flows through the indicator, through the switch, and through the signals. When the switch in the flasher is closed, current flows through the flasher because it is a direct short with less resistance than the indicator, then through the switch and signals. If all three lights are on at the same time, I'd suspect a wire is connected wrong somewhere.
Then I'd make sure the bulb sockets are clean and tight, followed by making sure the bulbs are securely in place and the filaments are properly suspended between their stanchions. Then I'd swap bulbs left-to-right front, check for operation, then rear, check for operation, adding di-electric grease to the bases so I never have to worry about them corroding again. If you swap the front bulbs side-to-side, and the left side starts working and the right side messes up, the problem is the bulb now in the right side. Then I'd think about cleaning and tightening all the plug-in wire connectors, and reassemble with di-electric grease so I'll never have to worry about them again. I'd also check the various connectors in the ground wire that runs all over the bike and make sure all connectors and lugs are clean, tight, and coated in di-electric grease. All of the above costs no more than a few squirts of Deep Creep and a dab or two of di-electric grease.
