We have a hibiscus in a self watering pot that is suddenly giving up the
ghost for no discernible reason. it has gone incredible droopy with many
of the leaves withering up.

it was not short of water at any point. i have examined the roots and they
seem alright, although in one or two places it might be the sheathing has
been nibbled or that it might have been some damage in getting the roots
out.

i was looking for weevil grubs, since i've had experience of them before,
but no sign of them. masses of small worms. any suggestions please as to
what might be going on?