Have you tried the 6 volt halogen bulbs from Goff? They were fitted to my GN400 along with relays, rather than the heated strip type flasher unit. They work brilliantly and give very positive on-off flashes. The system uses an electronic flasher which then triggers a 6 volt relay for each circuit i.e. left and right.
I didn’t install it but, if you want, I can figure out the circuit and send it to you.