Is the Freeview receiver broken?

We have a combined DVD recorder, player and Freeview box, Panasonic DMR-ES20DEB which has worked well for the last few years. Yesterday we found that the digital channels all have very bad colour - extreme red, blue or green with shadowing. DVDs however play normally and analogue channels are fine too, so the problem doesn't seem to be with the television or the connection between the DVD recorder and the TV.

We have tried returning the device to its factory settings, and then re-scanning the channels, but this hasn't helped. What is the most likely cause of the problem, and do we need to buy a new Freeview tuner?

Thank you for any advice or help.