Simple answer: The negative side of the diode bridge, the negative of the first filter cap, the input jack sleeve and the chassis should all be connected together. Furthermore they should be connected to the green wire of the power cord.
The exact details of those connections will affect the amount of hum you get. In particular, the connection between diode bridge negative and first filter cap negative needs a wire of its own, or you're guaranteed lots of hum. But it shouldn't stop the guitar signal. That points to some more fundamental mistake.