Headlight levelling

On my 1997 XK8, heading Level Adjustment has suddenly ceased to function. I have checked 5 amp. fuse and it’s ok. Also measured on Levelling Switch and by comparing to another found it ok as the values were the same. You could now believe it was the servomor. However, I do not believe that when they both ceased to function at the same time. Is there anyone who has a good idea!?!?