I have a triton mixer shower fitted & it has never worked properly. It is on a gravity system and when I hold the shower near the tray the pressure is pretty good but as I lift the shower the hot slows to a trickle. I have cleaned the filters in the head & controller & that's about as far as I can go. There is another shower in the next room right behind this one & is off the same pipework & works really well. Any help please. Thanks Neil