I would be inclined to check the level of the fork oil mate. It may be that it is low.
In fact it is very easy to just empty the old stuff out (it's probably very old and dirty by now) and put fresh stuff in.
If they are still way too soft, you could then put some heavier weight oil in which may help a little.
It is also a good move to check the preload setting is correct.
Changing this will not stop the forks diving, but it is as well to have everything set up properly before you go changing things!
Hope that helps you,
Jen.
