JLG40HA propane system question

Can anybody explain what item number 10 does
in this image? Item 10 is called the Filterlock.

Also, what is item number 20, the (Switch, vacuum), doing?

I want to take apart and clean and inspect for damage the
most likely things to go first on a propane system.

Something is not quite right, the engine seems to catch hold and start OK,
but only runs for a second or two. Once it’s running and warmed up,
it seems to be fine. It runs OK and restarts OK.
(does this sound familiar to you?...

JLG40HA propane system question

JLG40HA propane system question