Identifying Schematic Symbol (mysterious diode looking thing to replace)
Looks to me like a rotary switch.  

They are switches that you rotate to select the connection. (Do not confuse with a potentiometer, which dials a particular resistance.) 

The arrow represents the "wiper". I imagine that the numbers next to the nodes represent the rotation angle, or perhaps a setting that the user would select.

Rotary switches are commonly used as a mux/demux.