Weak shower flow

[Jeppol]

I had a mira coda shower installed last August, it replaced a 20 year old mira shower. We have a gravity fed system. The water pressure on the new shower has been very disappointing compared to the old shower. I had to get the plumber back after a couple of months to take a look & he was a bit baffled as to what the problem could be, he cleaned the filters & that improved it a bit but after a few weeks it went very weak again.
I contacted Mira showers a couple of months ago & they sent an engineer who took out the check valves & that seemed to do the trick, the shower was at a pressure similar to the old one, however, the flow has started to drop again & I'm getting a bit fed up with it. Could it be that the filters need cleaning occasionally & is that a job I could do myself?
Would be grateful for any advice.

 

[longdogs]

Would be worth checking the filters again, if there has been any work done to the mains supply in the area, the filters can clog up fairly quickly.

Turn off the water supplies
Drain the shower valve & hose
Undo the two big nuts at the back (on wall)
The filters will be inside the nuts.

Have you tried the shower without the head?, it could also be blocked.

Have you tried without the hose? It could be collapsed inside