If your very into the appearance of the headlights I would suggest changing both bulbs as the new bulb maybe a little brighter or whiter than the other also if one has gone the other has the same life left. I remember getting the 172 at the dealers and the guys telling me that a xenon bulb was £125 each but I had it 12 years/ 202,000 miles and only one bulb failed and I bought a pair of the original Philips 4400K for £48. Why not join the forum it's £5 a year and there should be a how-to section about removing the bumper the headlight has a bolt under it and to the side that most people miss and break the mount off.