Thanks, Rob. I've checked both. The filters are absolutely clean. Check valves are responding to air blow. I've also removed the shower head and dropped the hose as low as possible, but the flow remains low.
Hi billy_smith,
I am having the same problem as you did, except that after 2 days of firing the flow up by turning on tap at WHB, the trick does not work anymore. What was the problem and rectification for yours?