I have just purchased an X358 2.7 D.The windscreen washers worked but were a bit on the weak side. I topped the reservoir up and did a proof wash. Both headlamp and windscreen washers worked but I then noticed wash fluid leaking from the n/s headlight jet, next day the windscreen washers stopped working.

I disconnected the windscreen supply at the hose connector by the top of the reservoir so that I could gently backwash air through the pump (and presumably filter mesh) with an air line. Luckily I had some 3.5mm tube that would fit through the grid moulded over the inlet to the reservoir and fed that in to the bottom of the reservoir. This tube was then connected to a vacuum device with a catch tank. So the flushing proceedure was add 2 litres of warm water to the reservoir, give a purge of air at regular intervals, vacuum out from bottom of reservoir until empty. There was loads of muck came out in the first 2 litres and the 2nd.......10th, then it became clean water!

All works fine now!!

Well done. Got a 2009 Sovereign 2.7 myself and had exact same but I went down route of removing wheel, liner and bottle. A bit of a faff and took a few hours to move everything out of the way etc. But you wouldn't believe the gunk in there. Filters on outlets completely gunked up. It like a fire engine now!