Turn signal problems

[Fazerider]

I’ve had similar problems with mine in the past.
A continuity tester helped to find the poor contacts, the bulb-holder itself being one of them.
Where there is visible corrosion, scrape it clean, give the female connectors a squeeze with some pliers to tighten them, you should need to push them quite firmly to get the two halves to mate. Apply contact cleaner to all connections including the switch. Check you have continuity to chassis from the bulb-holder.