call the ford dealer I'm sure they'd be happy to help LOL, I know the bulb number itself is listed in the owners manual but not the part number of the socket...why dont you try rock auto.com? under electricial
1. Go to http://www.tousleyfordparts.com/
2. Select your Year
3. Select you Make (Ford)
4. Select your Model (Focus)
5. Once the next page loads with a list of items on the left, select "Front lamps"
6. Select "Headlamp components" once that selection expands.
7. Select "Socket"
8. Select "Signal Lamp Bulb"
Doesn't give you the part number, but that's how you can order a new one.