Wiggle the key- does that end the flashing?
The root cause is the pin not going in far enough. It's been a few years since I modified mine. I remember cutting a small piece similar to the pin, and adding to where the pin goes in. Sometimes when on a rough trail the indicators will flash. Just pushing the key in will correct it.The root cause is unclear - either the switch mounting or the incredibly frail pin that actuates it. The switch is large, and is held on the inner column - by one screw - and the attachment is one of the contact strips, not the body/shell of the switch so it can move around.