I'm not after a new power supply, just putting it out there that this seems to be a common problem.  I've been to a few open homes lately and all the houses I've been through that were empty, were missing the ONT PSU.  I didn't ask the agent if it has been put away somewhere, however its probably likely it was taken by whoever was last living in the house.

When we finally move to a new house, I'm probably going to do the same thing and take the ONT PSU with me to our new house.  If the ONT is the same at the new house, I wont have to mess around trying to get a replacement PSU.

My personal opinion, Chorus and other LFC's should probably look at integrating the PSU's into the ONT's to prevent this problem.  Perhaps a standard 3 pin IEC inlet that takes a "jug lead", as these cables are very common and almost everyone has one.