Hi!...why is that the simplest of diy jobs turn out to be the ones that go wrong!...? I wanted to change the tap head (including the brass ferrel innard parts inside. This was because the tap would only turn about one revolution and the flow was either weak then strong (all other taps have good pressure). Anyway so the first thing I did was gave the isolation valve screw under the sink a quarter turn so it was horizontal across the pipe. This turned the supply OFF to the tap BUT the isolation screw kept leaking..drip drip drip. The irony is I couldn`t get the tap off anyway after removing the cap and screw as it has been there for years and it was solid... so I reassembled tap as it was. After fiddling with the isolation screw for several minutes I finally got it to stop leaking (fingers crossed)....and the strange thing is the hot tap turns 3 revolutions like it should do and the flow is great!!!..even though i did not renew the innards!!...So i have 2 questions please. 1. I have read somewhere that if you do not get the isolation screw on the valve in EXACTLY the right place it can leak,..and you have to get it spot on or it will leak..is this true...AND do you think as it hasn't leaked for an hour with the tap on and off i will be ok? 2. Is it possible that some limescale or crud was caught in the isolation valve and i have released it so that now the flow is great although i don`t see how if i did dislodge some limescale that would make the tap have more turns now!??? Many thanks!