CRT width

I'm not too familiar with the TDA1170N, but it looks like it's a vertical deflection IC, similar to other ones that I've seen. I don't think any of the horizontal deflection functions are handled by this IC, so it wouldn't have any effect on the width of the raster (though, a caveat would be that it might have some influence on the pincushion correction, which does modulate width). In any case, I think it's more likely that something else broke in the process of swapping the part. Is the width currently in sort of a normal state, or is it way off?

I see, but a bright, horizontal line means that vertical deflection has failed. Horizontal deflection is still working just fine in that case. Failure of horizontal deflection almost always results in absolutely nothing on the CRT functioning because a lot of the circuitry depends on the flyback being driven by the horizontal deflection.