197 projector headlights too low

[wmg100]

Hi all, my first post on here. Have been a regular member on a few forums, mainly vx220.org and ph. Have had my 197 for a year and recently the projector headlights have started going to sleep. They will be absolutely fine, self leveling as they should and then they will just start to point down in their lowest setting. I've had various cars with self leveling xenons and this isn't just the sharp cut off that some people complain of, they're pointing at the ground to the point that they don't illuminate road signs. Then they'll wake up, do the little up and down procedure they do at statup and be fine again. Is this a commomn fault and could anyone point me in the direction of a fix? Cheers.