Tis painful until you get the idea. Panel was put in with boat on its keels. You are (as I) trying to do it with boat in water
- different. On mine, there was a slight bevel at the bottom of the panel (in or out I don't remember). remove the door frame and door for working room (some big screws, easy), put hydraulic jack with 2x4 to frame and base next to panel, nudge up ever so slightly since you are trying to spread a solid sheet of plywood
- too much and you will break the panel. Then some firm raps at the bottom 0f the panel and it pops out (or maybe the top - who knows how the workpeople at lagoon
actually installed the bevel edge). Since there is a bevel, one direction will move whereas the other won't. Inspecting with the door frame off should tell you. I believe I pounded to the aft of the boat but no guarantees. No I didn't need a header. Installed washer, did the slight spread again and couldn't get panel back in. I was afraid to apply too much pressure so I lightly sanded the beveled edge and in it went. Been locked in fine for 20k sea miles. Good luck.