Power problems - beware
The internal power supply fails. Both on the VX922 and the VX924. We've had an electronic engineer repair some of them, it seems to be an issue with the capacitors in the supply, but even these repairs aren't long lasting and he suspects there are other faulty components in the supply, or components that have been damaged by the original faults.
So if you see one second hand, it may not have much life left in it!