Plockmatic Fold Position Consistency...

[kdw75]

Our Plockmatic 350 from 2019 has recently started folding inconsistently. We had the tech here once so far and he calibrated the length jogger and said you can't expect perfection, even though it has been very consistent up until now.
What we are experiencing is that all stocks, coated, uncoated, cover and text will have the fold be off by about a 1/16" of an inch. Out of 10 books, you might have 1 or 2 out of position. It is creasing the books very consistently and the ones that are folded out of position have the crease right where it should be, but the fold didn't follow the crease.
Does anybody have any ideas where I could look or what I could suggest the tech take a look at?

 

[gregbatch]

Does the number of sheets affect behavior?

 

[kdw75]

I haven't checked extensively, but 3 different jobs with 2, 3, and 7 signatures all had the issue. I ran one with a 10pt cover and creased it on our press, and then hand fed it into the plock. Doing that fixed the issue, but of course that is a much more aggressive crease.