As far as restoring them, they are not more complex than most TVs of that era. However it isn't mechanically easy to work on them. The cabinet design of all the Predictas tends to cause high chassis temperature which lead to short life of many parts.
Here is one story.
https://www.antiqueradio.org/philc12.htm
Crist Rigotti on this forum has recently started to sell replacement networks (couplates). He has also restored one or two.
Do a search on this forum to find more info about peoples experiences with Predictas.