It is fairly easy.
In manual under burner head, electrode and valve assembly gives some information. Page 25 of previously posted manual
1) Turn off LP
2) Open outside access
3) disconnect LP line
4) look on right side of the gas valve, you should see two 1/4 headed sheat metal screws. Remove them. Easiest with 1/4 inch socket on 6 inch extention.
5) assembly should be loose and come out.
Harder to get back in as the screws are hard to reach with fingers. I use a piece of tape to hold screw in socket. Make sure it comes out with socket(tape)