Im looking for jp13 and I noticed that they have a different springs cover. I suppose that a newest guitar has two slots in a cover. I'm asking if they changed on JP 13 only this or anything else.
I think EMMM went to that trem plate across all models as it provides better access to the trem cavity. (ie. adjusting trem spring tension) I am not aware of any changes to the JP13, but if there is to be one it was only be because JP requested it.
Perfect comparison photos from Mordimer. New on the left, old on the right. On the new ones the Piezo pieces are wider, and there is only really the one contact point for the string (on the piezo). The old ones touched the saddle opening and then the piezo piece on their way out of the bridge.
I noticed the difference when I bought my JP7, which was made in 2014, compared to my 2013 JP6.