Uniserver, that SE need its monitor readjusted in width and height. It's supposed to be more wide than tall. The screen resolution is 512x342 after all! Height should be 4.7" (11.75cm) and width should be 7" (17.5cm) according to the service manual for SE and SE/30 by Apple themselves. Just check images of SE ads/commercials, the screen is not supposed to be like that.
It's kind of hard to measure and adjust it to a ruler, but it's worth the time for sure.
By the way, if you think the machine adjusted its width and height by itself over time, then it's probably a good idea to recap the analog board. Also clean those rotary potentiometers while you're at it.
If you're a maniac just like me, then go ahead and check if any resistors on the analog board are out of spec by desoldering one leg and test them, one at the time. Especially those in the vertical and horizontal deflection circuit.
It's kind of hard to measure and adjust it to a ruler, but it's worth the time for sure.
By the way, if you think the machine adjusted its width and height by itself over time, then it's probably a good idea to recap the analog board. Also clean those rotary potentiometers while you're at it.
If you're a maniac just like me, then go ahead and check if any resistors on the analog board are out of spec by desoldering one leg and test them, one at the time. Especially those in the vertical and horizontal deflection circuit.