I have a Bis as well. I found that 10 out of 10 times when there was an electrical fault, at least in my case, the cause was either a loose connection or the contacts were poor. Today my right indicator decided not to work. It was not blinking on right turn. Thought it was a busted bulb. Turns out the bulb simply decided to come loose, so was causing the circuit to malfunction. One time my sidelights decided not to work, turned out contact on one of the sockets was faulty. It worked when one touches it but does not when you let go - weird! Have lots of similar stories to tell. Knock on wood, all were nothing serious.
Just check out the connections, clean the contact points and just fiddle with the bulbs. As mentioned earlier, any loose connection or bad contacts, cause the relevant circuits to go funny.
