Install the threaded insert if you haven't already done that.
Carefully cut away the erupted area on the top of the CP.
Install the joystick and screws to ensure that the next steps don't make a plug that gets pushed out when you install the joystick screws.

Use a piece of tape/thin weatherstripping to keep the Bondo from getting on/into the threads of the screw and insert.
Fill with Bondo and let it dry completely -- you may want to do this in 2 layers, depending on the depth.

Remove the screws and joystick so they don't get dusty during sanding.
Sand the bondo smooth.
Prime and paint.
Enjoy.

Scott