For several years I have had four HD units - all on the same circuit. Within a few months, two of them went out. So I ordered two of these lamps, installed them and - nothing. So don't think the bulbs are bad. The lamps were to blame, although there were no signs of internal damage. They even had a normal "hum" when turned on. New replacement bulbs worked fine in other lights. Too bad I didn't take the time to look at them beforehand. But I'll keep the old bulbs as spares and put the new ones (they're a bit brighter when they're new) in the work lights. I then converted the faulty lights to LEDs by removing the ballasts and plugging the outlet directly into the line-in. With the new 15W/5000K LED lamps, they are just as bright as ever. So if you have another working headlight, test your "bad" bulbs in it before purchasing a replacement. In any case, a good reason to convert the lamp to LED and save even more energy. They fit the same socket as HD incandescent bulbs - just remove the ballast and plug straight in.
E12 Led Bulb Dimmable 4W 5000K Daylight, Type B Light Bulb Golspark 60W Equivalent, E12 Small Base Candelabra Led Light Bulbs, B11 Chandelier Candle Light Bulbs For Fan Light, Flame Tip, 550LM, 6 Pack
20 Review
CHANZON 100Pcs (10 Colors X 10Pcs) 3Mm LED Diode Lights Assortment (Clear Transparent Lens) Emitting Lighting Bulb Lamp Assorted Kit Variety Colour Warm White Red Yellow Green Blue Orange UV Pink
41 Review
π‘ GoodBulb LU70/MED - 70W E26 High Pressure Sodium HID Bulb, 2000K Warm White - 2 Pack
7 Review
Pack Of 2 Grensk Dimmable T20 LED Light Bulbs - 40W Equivalent E12 Candelabra Bulbs For Ranges & Fridges, 2200K Warm White With 350 Lumens Output For Wall Sconces
9 Review
20 Pack 5CCT 4FT LED T8 Ballast Bypass Type B Light Tube, UL/FCC Certified - 18W, 2300Lm, 3000K-6500K Selectable
21 Review
Bulbrite A19 Solana WiFi Connected LED Alexa Smart Light Bulb, Single-A19, Tunable 2200K-6500K Color Temperature, Frost Finish
28 Review
Luminescent lamp Camelion 11066 ultraviolet, E27, 26 W
12 Review
Lamp LED Ergolux 13638, E27, A60, 15 W, 4500 K
12 Review