Welcome Scott.... [smiley=thumbsup.gif]
It could be many things of course, given that it is a used machine but one thing worth checking, is whether the 3-Way Valve is working properly. They are normally fitted as per the attached drawing from a Bezzera spare parts manual (under the green circle).
Sometimes the mechanical components of the valve get gummed up with coffee residue and more or less, seize up. They are quite simple to remove, disassemble and clean up. It may also be possible that the solenoid coil is faulty and thereby not actuating the valve mechanics. Id give the clean-up routine a go first though before worrying about the coil.
All the best mate.... :)