New Holland round baler rb560 slipclutch

Smoked my slip clutch a little bit the other day on a wet slug. Baler then continued to plug/slip until I checked the book and realized my slip clutch plates were 10-15mm further apart than the book says they should be. Keep in my this is the 2nd yr for this baler & it has never been adjusted before. My question is, is this normal for a slip clutch to wear in / have to be adjusted after the first yr or so of use? Does 10 or so mm make that big a difference or is something else going on? I don't want to tighten it up just to break something else. Thanks in advance for the replies

New Holland round baler rb560 slipclutch