I read a thread today that had a couple of members saying they have come across lots of leaking worcester hex's whats the best way to check im thinking isolate the boiler and leave the sump cover off tgen check for pressure drop and water in the sump? I am the unfortunate owner of a Woosy Tosch 28i junior. Its dropping pressure like nobodys business and prv exp vessel are fine and there are no leaky rads. Is this a common fault on these?