Lucas type SF40L-90. 12V, 3W 'fuse' style bulb.
Check clean and free moving, replace bulbs and occasionally a drop of thin machine oil to the arm pivot. For more details click on the image below
Lamp may fail to light due to blown bulb, faulty wiring or poor electrical contact (especially for SF80). Check the contact between the metal arm cover and bodywork and that the spring and lamp contact is free from corrosion.
Arm may fail to raise (partially) due to mechanical damage or grease/dirt accumulation in the mechanism.
Arm may fail to raise at all for similar reasons but also check electrical connectivity, fuses, arm fouling bodywork and damage to backplate.
To be written...
The later (1952?), Lucas type SF80 (round coil) trafficators have also been found to be suitable. These may have been fitted as standard in the last 400 or so Barker LD10's.
Orange semaphore arms and stainless steel covers for the SF80 are available from Vintage Supplies Ltd. as parts #215, #215B respectively. These may also fit the SF40 (although it originally had yellow semaphore arms).
The SF40 lamp lit as the action (of raising the arm) commenced, the SF80 lamp only lights when the arm is completely raised.
The SF40
The SF80
None yet.