Old showerhead always came out with little pressure and unevenly. Cleaning didn’t help much so I looked for a new one. I found a seller that manufactured locally and specialized in showerheads. Much better than the attractive plastic junk from the box stores.
It was an easy change and it makes a big difference.
It’s a metal pipe going from behind the shower unit (picture an upside down ‘J’. Behind the unit it’s connected to the backside of the tap. What happend is that the head had been on it for several years and lime from the water was depostited between the threads. This somehow made a solid bond. And by apply more and more force eventually the lime won from the metal of the pipe. Cutting the pipe just above the thread cleaner than you could with a pipe cutting tool.