Frame out of square

I am assembling a Geeetech Prusa I3 Pro B that I recently purchased.
I have a problem making the Y axis parallel to the X axis.
The Y axis was assembled correctly and square.
The problem is in the acrylic supports of the x axis. The problem seems to be in the laser cuts of the acrylic being badly out of square (the cuts are not perpendicular to the surface of the parts) so when they are assembled the whole assembly sits askew and for this reason it is impossible to mount the y axis square with the X axis.
I would like to know if anyone incurred in this problem and how it was solved.
I have been evaluating rebuilding the whole acrylic frame out of MDF and discarding the acrylic pieces , or routing the cuts to make them square.
Maybe there is a less radical solution to the problem ?
We're talking 3-4 mm out of square on the width of the side supports at the base.

Did you solve this problem? My Geeetech pro is also way out of square. I have used it for over a year, not knowing about it. Seems worse now than ever! Measuring old prints shows out of square but not as bad.

Only way to fix it is to replace the acrylic with something else.. alu or better.

Yeah, I’ve known mine is squint and been trying to come up with a clever solution as I don’t have any tools at my student flat. One I came up with and did try was to use two threaded rods from the front of the y assembly to the Z motors to adjust and triangulate. However that ended up actually pulling the bottom of the Z assembly and making THAT problematic...
I’ve seen several printed braces that hold the Y threaded rods at other points too buuuut the problem is they all have one huge flaw: any squint in the printer when printing will be translated to the brace and not help at all, in fact it could make matters worse. A catch 22.

Hello there,
I have made two 3D printers from scratch including one Prusa I3. If you send me a picture showing the problem, I may be able to help you. There are always solutions.

Vic