PeterC coughed up some electrons that declared:

On Sat, 24 Jan 2009 21:38:55 +0000, Tim S wrote:

What I'm considering doing is to drill some 10mm holes in the dodgey
places and pour in neat SBR until it wont take anymore, in the hope of
stabilising the crap under the levelling compound (which itself is solid
and firm).

Might be best done through a tube if possible, so that it fills up from
the bottom.

Funnily enough I was thinking something like that - with plastic funnels
Poke them in, fill up and have coffee.

Cheers

Tim