I am getting poor hot water from my Baxi 105e (hot at first then dies away). I have checked the gauze filter on the cold water inlet, that was OK. Went to change the DHW diaphragm last night, but I had the wrong one (possibly from an Instant - they look smaller) so a correct one on order. Before I get somebody in I want to check the filter on the manifold attached to the plate heat exchanger. I had the whole CH powerflushed a few months ago as it was full of debris. Can this filter get blocked by debris out of the CH circulation water? If so, what do I need to drain down or isolate to remove this filter? I'm not sure what is referred to as the primary system in the instructions. Thanks in advance for any help.