bath leak

Hi All, I've recently removed the panel from my bath to change it and noticed there is an area of crumbling plaster at the shower end of the bath where the screen attaches and the plaster is slightly damp behind the bath. Thankfully the floor doesn't look like it's affected. It looks like the...

I am having a problems with a relatively straight forward job, the nut that connects to the screw for the plughole broke/vanished and the bath started leaking. I replaced the whole waste/overflow with a new one of the same type, however, when I'm trying to get it aligned with the bath hole, and...