jozefcj , it is not possible to tell which firmware would work properly on your player, so i'll suggest that you do a trial and error method on firmwares.
As you have remembered and the chip is CTW500, the player uses the v9.0.48 firmware. So try all the v9.0.48 for your screen size here
http://www.mympxplayer.org/actions-9...mare-dc37.html
If they do not work, try the other v9.0.43, v9.0.50, etc as well.