Outback Solid Handle screw replacement

My solid handle (starboard side) lost a screw and I ordered a replacement but can not figure out how to assemble or disassemble the solid handle. I can't figure out how to get the screw in the handle or tighten it. If anyone has any instructions, I would appreciate the help.

The only trick I know is to get a really skinny flat head screw driver. Just replaced one the other week. It was a tight fit even using a thin screw driver. If there's a dealer nearby, take it to them, they usually have a tool like that handy.