New cylinder issue

I recently received the 500 cylinder only to find that it's not firing. It appears that the teeth from the gear is not grabbing the piston to pull the spring back. I switched back to the original cylinder (350) and it fired fine. Anyone have any thoughts as to why this may happen or suggestions to fixing the problem? Thanks.

The piston could be getting pushed by the spring in a weird way which could possibly be bending the piston upwards and just out of reach of the gears.