Impression pressure in Windmill 34x46 getting low for Diecut

Hi we have been using this old machine since 4 years and about million impression die cut. Now the impression pressure needs to be set high (about 18-20) for the same job which ran perfectly at about 6 or 7 previously. The safety pin is not damaged and bushes also seems fine. What may be the reason ? Or the main bushes wore out? Can anyone figure out or advise?

 

have you changed your underlay sheets recently?

 

May be main bush at the buttom wore out.