satnav mount on norge

when I brought the norge it was supplied with the origonal TomTom rider which worked OK
as with all things electronic it eventualy failed (or was it just me) I obtained a rider 400 and mount which I stuck in the same place as the origonal, on the cover plate on the top of the headstock. It works almost alright but the screen is invisible if the sun shines over my shoulder. I have seen other norges with a mount across the screen supports. Has anyone any idea where these come from? I tried to knock one up but it didn’t look very good.