Paslode im350

Hi wondering if anyone can offer any advice. My framing nail gun has stopped working. I've stripped it down and tested it. I get a spark, fan works and everything is as it should be, however.....
I can get a spark when it's stripped because I press the spring lever button to create the spark. When the unit is back together i get no spark and I can't see what would press the lever to create the spark as the piston housing falls short of pressing it. I've taken a couple of photos, on with the gun not depressed and the other depressed. As you can see, the lever is not contacted???