Same file, perfect when using old rep 2 and gaps when printing on newer machines

Hey guys! I have a problem that even the manufacturer don't know how to fix. I have 3 MakerBot Replicator 2, two of them are the younger version and one is the older one. Some files that I print, comes with a "gap" in the same place when they are printed by the two younger ones as the old always "close" these prints. Follows an illustrative photo. The piece on the left side was printed in the old and the right side - that has the gap - in the upper right corner. Any idea what might cause this? All files are corrected and all printers have the latest firmware update for the MakerBot. Thank you all for the help!

Attachment 5787

I can see that as well in other places (close to right eye for instance). Am I right to assume that this happens everytime the printer ends the perimeter layer of an "island" ? If it's not the case, ignore all the text below.

For that kind of hysteresis behaviour, I would look in 2 places :
- Did you set a command that stops extrusion before end of move ? (I sometimes use that in S3D to limit ooze, but not 1mm, ususally 0,1mm or so).
- Are you belts tight ? I suggest to make it do a simple cylinder or a cube and you should see the same phenomenon again.

If you can't eradicate it, you should be able to hide it by forcing you printer to use random starting points rather than the "optimize for speed" parameter that ends up always starting at the same points.

Yes LambdaFF, every time it ends a perimeter the "island" shows up. This islands are not the entire wall length, just in the middle, most of edges and bases close above and under the islands.

I'll contact makerbot support to know how can i check the belts and how changing the values (i don't know how to modify it, we prepare the final file in a factory default app).

Cheers!