Thank you for your help. Unfortunately I had already discovered the first site & unlocked the Teac player (& the Phillips was a multi-region to start with).
As I can play some of the region 1 DVDs I guessed that the others must have something extra added to stop multi-region players from playing them
(I searched the net & I tried the trick of playing a region 1 DVD that did work before loading the ones that don't, without any luck).
So I wanted to make one of my DVD players a dedicated region 1 player (in the hope that would do the trick) but I don't know of any hack sites that will do that.
Maybe no such site exists. Does anyone have any other bright ideas?
(or do I have to buy yet another DVD player?)