Set your meter on the 20v setting, touch the red lead to the top cap screw and the black lead to the top or bottom cap, then push the fire button.
I understanf if you aren't comfortable opening it up, I'm thinking that the wire may be loose causing intermittent firing. Check and see if the top cap outer screw is tight. It needs to ne snug but not super tight.
I understanf if you aren't comfortable opening it up, I'm thinking that the wire may be loose causing intermittent firing. Check and see if the top cap outer screw is tight. It needs to ne snug but not super tight.