triton rapid 4+ shower problems with low pressure detection?

We purchased our triton rapid 4+ shower about eighteen months ago and it worked ok until recently when the low pressure led and the cold led come on when you select the hot water selection and it takes tIme until this led comes on and the water gets hot and it somtimes goes through a phase of flashing between the led,s. I suspected that i had a blockage in the filter which i checked and and found the filter clear and i also ran the water through and found that the pressure seems adequate.