Stephen,

I hope what you mean by that is that the screws are not fastening directly
to the epoxy.  The last thing you want the next time your step pulls out is
that it takes the epoxy with it.

If using a larger diameter screw does not hold the step because the
underlying step block is too rotten, inject filler epoxy and before it
cures, press 3/8" wood dowels into the screw positions.  After it dries,
you can remount your mast step by screwing into the dowels.

Regards,

Rick Lange