On Oct 2, 7:21 am, "STephen" wrote:
A previous owner has actually drilled 2 inch holes into the middle of every
riser so I tried to insert the claw of the hammer into the hole to pull up
the riser but that didnt work.

Might be worth wedging/jacking the two stringers apart /just a little/
to see if that frees the riser up, maybe the riser is being pinched
between them.

cheers,
Pete.