If yours uses a thermal sensing element (not just mixing blind),I’ve found running it through its full temperature range helps a lot. I suspect limescale and other crap build up on the thermal element. It adds several years on to the life of the mixer. Descaling it would likely also work, but involves removing it from the pipes, to get the cleaner in.
Where I live, I have to spend 500 years to either get volcano-like water, or Ice Age water. Moving it one atom completely changes the temperature.
If yours uses a thermal sensing element (not just mixing blind),I’ve found running it through its full temperature range helps a lot. I suspect limescale and other crap build up on the thermal element. It adds several years on to the life of the mixer. Descaling it would likely also work, but involves removing it from the pipes, to get the cleaner in.