NH 499 roll gap adjustment

On my new to me NH 499 I feel that I am not getting enough of a crimp on the stems of the hay. To me it looks like the rollers have too wide of a gap. I was going to adjust the roll gap clearance by removing some of the shims like the manual stated but I can't figure out how to release the pressure from the shims to be able to remove some. The manual doesn't say anything about how to release the pressure......it just says removed the bolt that holds the shims and remove enough shims to get the desired roll clearance. Anyone know what I need to do to get the pressure off the shims so I can remove some?

NH 499 roll gap adjustment