inconsistant hot water from baxi 105e combi boiler

[machrie]

After two visits from a heating engineer and replacement of the pressure switch and the diaphram I still cannot rely on hot water from the shower or h water taps
The following symptoms appears when the system doesn't work ,.50deg red neon flashes, green hw/Rad neon light, and the amber neon flashes as the system tries to fire up
The pump runs very hot and more than a trickle of water appears when the centre chrome nut is loosened. Is the pump on the road out ???????
The upstairs shower very rarely delivers hot water
ANY HELP OR ADVICE WOULD BE APPRIECIATED

 

[bengasman]

Pump has nothing to do with it.
Most common problem on these is poor installation and/or lack of proper maintenance have caused corrosion leading to failure of the diverter and/or blockage of the hex.