Greg,
To test the firing pin function is very simple. First, no magazine and verify chamber is empty.
Get a pencil with an eraser in good shape. Put pencil into muzzle eraser first. Hold gun up to keep eraser down into chamber. Cock hammer and pull trigger. Pencil should pop out of the muzzle from the force of the pin hitting the eraser. If it doesn't then there is a problem with firing pin, spring, roll pin or dirt in pin channel.