Suddenly lost high beams only. Not bulbs (very unlikely with both at once), not the relay, and the switch feels firm and as it should. Is there anything else in the system that I am missing? Has anybody else had a switch go out.
I work on loads of Miatas and never had this issue before. Thanks

 

Check the grounds? That's a strange one.

Is power making it to the bulbs? Test at each point and walk backwards to the source of the fault.

 

Ground is good - low beams are as bright as ever. Switched out relay with another car. Have found in car test procedure for the combination switch so that is next step.