Hi @bm, All drains will have a certain amount of buildup within them. It's a bit hard to tell, but if that's a 50mm pipe, then it looks about right. ...

Hi @bm, The drain cover removes with a 1/4 turn anti-clockwise. If you use needle-nosed pliers, they should give you more purchase on the cover. ...

It looks like the water is bypassing the packing ring around the stem. Most gate valves have a packing ring around the stem to stop the fluid leaking ...

@bm Regarding low water pressure, and initial cause of leaking gate valve: Have you checked for debris inside the tank, ? gate valves don't do well ...