Look at the bottom of the rocker. You will see a round plastic plug about a foot back from the front edge of the rocker. Pop that out (careful about that so you don't get yer Saturday night bath early..
). That will solve your immidate problem.
The slits are a bit harder to locate.
Get on your back and study the back side of the pinchweld wher the inner and outer rockers come togther. About a foot back from the font edge you will see a slit, near the bottom edge, that is on the
inner vertical surface. You can use a zip tie, as you would a rifle cleaning rod, to clear the drain.