Pretty much impossible to get it right that way and there's
likely none there right now, so ... IMO, much better to pull
the tub out, especially since it's such a light one - hardest job
will be getting to the screws that fasten it to the wall if there
are any. Even if it were cast iron, I'd pull the tub out so
everything could be inspected and done up right.

Pop


Joe Bobst wrote:
However my concern now is not just slight flex, but major
flexing. I'm worried that the foundation that the tub sits on
is not
right,

Some low priced tubs must be bedded in a leveling compound or
mortar
during installation. If you are stuck with one of those, you
will
have to access the tub bottom via an opposite wall.to shovel
in the
levelling material. Tough call, as it will be quite a project
no
matter if you fix or replace. For now, use another shower if
you
have one while you ponder the best course to take. Gioiod
luck.

Joe.