Hi i have a mira essential electric shower and on some occasions the low pressure light turns on & only a trickle of water comes out but some times it works perfect. I also have a power shower running off the normal hot water system which if is used for about 5 mins and then turn it off and then turn the electric shower on 9.9 times out of 10 the electric shower will then work! strange. Any idea of what could be wrong with the electric shower? i have cleaned the head and internal filter(which was clean.)