In the drawing, I've drawn a redline to the screen. Remove the four screws on the diaphragm cover, GENTLY remove the diaphragm, and you will see the screen. It's very obvious once you get in there.
The pics are of my non-DL engine, but nearly exactly the same carb, just mounted differently. Hope these help!

P.S. - the pic is a generic Walbro, and contains other troubleshooting hints - might be worth keeping. The pump cover, screws, diaphragm pump, etc. are the same for our carbs.