Thermoflex Imaging Error

[Nigel Wild]

Help please with an intermittent, problem when imaging sleeves,

It is almost like a rotary encoder issue, where the start point around the drum appears to be shifting. causing the image to spiral in the fast scan direction.

If we expose the same tiff file again, all is OK

This occurs at different size repeats, 550mm & 450mm and the same adapters are used with our CDI with no problem so we don't think the sleeve is slipping during exposure.

any suggestions to isolate the problem would be appreciated.