If you look at the second picture you will see that there is a gap between the top of the finger and the underside of the sliding knife. To achieve a clean cut without jamming the gap needs to be closed up- at the moment it will be the same as using a pair of scissors with the pivot screw undone.
To adjust the gap you normally slide the moving knife out of the side of the cutter bar and stretch a piece of string across the fingers where the knife slides, then you can bend the fingers up or down so that the cutting edges just touch the string. In theory, when you replace the sliding knife you will achieve a smooth scissor action on each side of every finger. It takes a bit of time to get it right but you will find a world of difference once you’ve done it. At present it will be like cutting wet cardboard with a blunt pair of scissors- it just doesn’t work!
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