One of the cassettes/valves in my bath mixer tap has gone, so I'm trying to get it out. I can remove the handle but am unable to unscrew the bonnet (see photo). I'm using grips but it's not made any easier by it being a sloping surface. I've tried spraying WD-40 and descaler around the base and inside, and also a strap wrench. Also given it a bit of a bang with a hammer, but nothing seems to work. Grateful for any suggestions. I've seen someone suggesting pouring boilling water over it, but will that damage the sealant around the bath? I really don't want to get into having to get someone to take the bath out (that's if I can find someone willing to do it).
Thanks
Thanks
