Heidelberg Platen Windmill Grippers creasing stock

Hello! We are setting up another Heidelberg Platen in our studio and have come across a problem we have not encountered with our other Heidelberg platens before - the grippers seem to grip too hard and are leaving creases about 5mm in from the edge of the stock. This happens on both grippers.

We are running 300gsm Lettra which is our usual inhouse stock, and all settings elsewhere are set for this weight of stock.

Anyone encountered this before and any problem solving suggestions?

Many thanks!

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check that the crease appears while in the platen and not during transfer at the gripper sucker point . if it is occuring during impression you are over packed and probably not running with lays , if you are holding the sheet constantly the sheet can mark along the gripper for reasons like the grippers face is not evenly aligned with the platen ,thick material and packing make this difficult to eliminate as there is no real adjustment you can make without the tools to tweak the gripper assembly , it is best you get an engineer who knows how to remove the assembly and level everything properly , overstressing the cast parts of the head is to be avoided the parts are many hundred dollars if you break them . it is possible to check the clearance is even down the gripper length both grippers should be similar off the platen bed ,3 /16 or so is not far wrong .(without any covering on platen ) As you have others on sight you have a comparison ,it may be as simple as a twisted gripper but most likely its the heavy stock being at the limit of the machine , there are some that just stand out as a bit troublesome ,in normal use it would never be noticed ,

I would suggest…. Mel Wrolstad, of Plymouth, Minnesota a retired serviceman from Heidelberg. He was able to help me over the phone. Yes he charges for over the phone service. He helped me tremendously. His contact number is (763) 473-5806

Thanks Theo, we have very little packing and no impression on and the press is running with lays. It also occurs even if we run the paper through without using any impression - so I think its something in the gripper suction. The platen is on a slightly unleveled surface (old floor boards) which may be causing the issue as previously we had the platen on a concrete floor, however our other platens are also now on this flooring without any issues. We have a technician here in Australia we might get to come have a look as we are quite stumped!