and you'll see for each set there is a chip with a '10' in the filename - it's that one which you'll need, but you do need to determine which version of the code that you have.
It's also possible that you have a dodgy socket for that chip, or it may even be a chip select problem, in other words another (soldered in) IC on the board could be at fault.
Still, worth trying the EPROM first then go on from there.