MZ790 Image Warping on Drum

[mixedfeelings]

Hello all,
I am experiencing a maddening registration issue with the second drum in my MZ. The image seems to be warped as it wraps around the drum, meaning that I can get usually get 3 or 4 (if i am very, very lucky) corners to register, but the center will be off. Conversely, when I register the center, the edges are off. I am not near my machine right now, but here is a digital approximation of what I see when I print test mode 81 (though my second drum is a little more skewed..):

Screenshot 2017-04-28 04.01.45.jpg

Blue is the first position, red is second drum.

It happens on multiple drums.

Has anyone experienced this? Is it even correctable?

Thanks in advance!

[20gaugeO/U]

Either impression roller that is bowed will cause the master to load a little crooked. Plus Riso has always had a +/- 2mm(???) tolerance for registration anyways when printing at 130 ppm. Spot color is supposed to be next to each other, not on top of each other anyways. You may be splitting hairs anyways but I've never tried this.

Good luck