Advice much sought Gents. I,ve got a leaking bath waste which taps into a 4 inch plastic soil system via a Marley 40mm strap on boss(ie 50mm hole drilled into soil pipe, solvent applied, boss into hole, and a pipe clamp) The leak is between the boss and soil pipe which suggests to me a solvent gap, and though slight it is a leak nevertheless which needs curing. The guilty joint is between the joists underfloor and space is tight so I,d really like to use the existing hole to drain the bath. So, how does one seal this? Can the old boss be removed and replaced with a new one and new solvent applied, or does it need blanking off and a new 50mm hole cut with a new boss. Or is there an easier solution.(Hate to suggest it but mastic???)