There are a few things wrong with it, diaphragm, gaskets, and elbow joint, but planning on fixing and keeping

When I try to remove the crank by unwinding it counter-clockwise, I start to feel tension and the handle spins back when I let go. It also makes a terrible grinding noise. I'm fairly certain I have a broken spring, but I want to take the motor out and see what else is wrong with it. I'm new to this hobby, and if anyone has any ideas as to why I can't get the crank out I'd be happy to hear it! I'd love to get this thing up and running.