Dog-Eared Documents from Canon IRAC7565i Booklet Finisher

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Canon IRAC7565 with booklet finisher - (output from finisher is a4 paper and labels. Label are stapled onto top sheet) On output the documents are slightly dog eared on the top right of each corner.
Machine is running at full tilt, labels are stacked in the high capacity paper deck and normal A4 paper is in 3 of 4 paper trays.

Any pointers as to how to get rid of the dog ears??

Thanks
Jay