How can I fix my shower, Triton T100E?

MY Triton T100E has developed a problem as the water is coming out of a pipe located directly behind the hose feed pipe and will only come out of the shower head when the head is placed in the bath. I have cleaned the shower head of scale and that is now running freely but the water will not flow through the feedpipe to the shower head when placed on its cradle on the wall. There are no indicator lights showing low pressure or overheat. Any advise would be gratefully received.