No Hot water, Fixed and Broken Again Ideal Logic 24

Ideal Logic 24, Previous problem was that the hot water was only cold or barely warm if the heating was in use. If heating was off and boiler cold then would get hot water most of the time. Changing the flow cartridge about 2 years ago (when I moved in) solved this problem enough to suffer it as I have a dishwasher and electric shower. Over time this gradually got worse. Until I had to fix it. Changed the flow sensor and the manifold, still not working. Changed the diverter cartridge manifold and diverter actuator , inspected the heat plate which appears to be in very good condition. Put it all back together and this at first appeared to fix all issues , lasted about 4 days and then very quickly declined back to no hot water. Not even tepid now but completely cold. If I remove the actuator and manually press in the diverter valve you then again have hot water. I've checked that all connections on the actuator are good. When there is no hot water it is heating up the central heating system. Can any body help. Also how much pressure is required to push in the diverter valve.