Opportunity is missed by most people because it is dressed in overalls and looks like work. - Thomas Edison
My guess is that it's not your Stop blocks, or your Tri-Loc pallet, but something else, such as something causing your frames to be contorted or something.You have a DTS correct? Try taking one frame on press, that is clearly showing an issue, (Measure the distance of the issue) and the document the location of that block or blocks. Then take that same screen back onto the DTS. I assume you have Tr-Loc or something similar on that. I assume.If the measurements are very similar to almost exact on both areas (Press and DTS). Then it should be registering properly (as it relates to the screen).The only way the tri-Loc would be higher/lower/closer would be if it were dropped hard, thrown into a brick wall, or pounded with a hammer or something. If it was good last year, it should be good this year. So if it was good last year, and you haven't dropped it/thrown it, then your issues is something outside of the Tri-Loc.There have been cases where a press operator has spun the press around unintentionally, smashing into a half positioned Tri-loc. This then, bent up the whole print head and Tri-Loc. They thrashed both. So I've heard anyways.
I really can't tell anything from that pic. Like what is that? Your level I suppose. But from the pick the gap looks even across. (in the pic). Are you setting the 40" level across the blocks and saying that one is higher by 2 mm? If so, then no worries. That's a little lover 1/16" and yes, I can see that happening. Gluing, mounting, drilling a hole higher than the one on the other end. But that's not important. The question would be, (do all three, make the needed contact) on the frames? If so, then no worries.You mentioned they did not (on some). This seems more like a frame issue. A tad Higher or lower doesn't matter. If one were to be fatter, or moved in closed to the frame and not mounted properly then I can see an issue with reg. but that's not what you have described.If it was good last year, it's gonna be good this year (unless, something happened to it).Give the measuring a try and compare to what it is in your DTS. You may find it interesting.Anyone ever had a block o the Tri-Loc move? Up, Down, sideways? I don't know how they mount them, but I suspect the are welded.