yaar
u wasted money in buying new, even at shershah in khi they used to same proc. of cleaning,
if u wanna clean they will open your rear & front light, wash it in tap water & dip them full in bucket full of water with ordinary surf foam & "red acid" which r available in sunday bazar for cleaning toilets/kitchen
they dip it for 3-4 hours, then during this rub with tooth brush, after that dry for 15 min. & light cleans like new(sp. yellowness removed by this)
1st i dont believe but one time i experienced them for mehran light, they took 150-200 for both rear & front & it really cleans/shine
u can do it at your own too