The decompression valve is not missing, if the saw is stock. The boss is there but has not been machined out for the valve. It is the same as a husqvarna 340. I have the husky version. the brake handle is from a husky, that is why it looks off. Huskys have angled handles and jonsered have strait across handles. The original intake boot has a plastic clamp that is prone to leaks there is an upgrade to a metal clamp that should be done. They are good little saws and can easily be upgraded from stock 40cc, to 50cc with a 346xp or 353 cylinder. They also respond well to a muffler mod.