BD 650 red raster smaller than others

I'm having a little problem with my barco data 650 crt. The red raster isn't as tall as green and blue. The width is the same but height isn't. I've adjusted the yokes so that they're as close to the tube bell as possible, but it didn't have any effect.

Is there a control where I can adjust the height of the rasters individually? If not, can anyone tell me where the problem might be? Neckboard, rgb output amplifier or rgb analog input.

I'm suspecting the analog input card as I had to change few transistors on that card. It had a problem with blue tube.

The blue tube wouldn't light up properly, so I changed the transistors for blue and green color. I couldn't change them for red as I ran out spares

I'm getting a new rgb analog input card next week, but I'd like to know if there's something else i've missed? Thank you.