Just putting new bulbs and sockets in may not work. I bend the contacts in the socket closer together, use the dielectric grease and that seems to work. I've heard good reports about the glass based bulbs, IPD has been mentioned but any auto store has the bulbs as well. I have also replaced the glass based bulbs with arking on the contacts causing the rapid operation of the turn signal as well. I think the pinching of the socket contacts closer together, grease and the Black based volvo bulbs or the glass based ones stand a better change of being a fix (short of redesign).