The boiler has been working fine for hot water but never been great 10lpm cold main. 4 lpm hot water. Removing the flow restrictor has improved it but has this affected the differential pressure either side of the diaphragm ??
Possible just a blocked condense line, as it shudders. Make sure the white pipe under the boiler is clear. This can happen if a washing machine is connected to the same waste pipe and blocks. EA is burner lockout.
Ive got an HRM Combi which had slow hot water flow. Removed the flow restrictor as the mains is poor also. Now the flow switch wont operate. Diaphragm in good order. Does it need the flow restrictor and spring assembly to create a differential in the diaphragm assembly ??