Hi, I have an approx 10 year old Mira Silver shower mixer that over the past month has been getting cooler and cooler. Today even the hottest setting was too cold for a comfortable shower so I decided to try to adjust the temperature setting. I found the manual online here https://www.plumbworld.co.uk/docume...r-shower-installation-user-guide-11628003.pdf Page 28 has the instructions for adjusting the temperature. I am stuck on step 2, I cannot seem to get access to the grub screw, I can't even see it! When I turn the control lever I can see the metal housing of it spinning through the hole where the grub screw should be, however no matter where I turn it there is no grub screw, just metal.