HP 82240B print graphics in right proportions?

[Aquarius]

Hey guys, I am printing plots and GROB's on a HP 82240B printer with the HP 48/50 calculator and it all works as expected. The only issue I am facing, is that it seems like the vertical distance between dots are larger than the horizontal distance between the dots.
To illustrate, if I print a 5x5 square it will look more like a rectangle:

. . . . .
. . . . .
. . . . .
. . . . .
. . . . .

This means that every graphic that is printed will be stretched along the vertical axes (square -> rectangle, circle -> ellipsoid etc.).

Does anyone have a suggestion as to why this is the case and maybe some ideas to counter it - as I would really like for my printed GROB's to have the same proportions as they have when viewed on the screen or just at least be able to print a perfect circle instead of a ellipse.