Replacement Calibration Plates

Just received my Otter and am learning and working on calibration. I get the sense that the Calibration Plates may be specific to each individual scanner? Just curious if these plates are available as a replacement part because they seem very fragile and it would really stink if a broken or scratched plate renders the entire scanner useless. Also, I’ve been having some trouble performing the calibration and I do see a few smudges of black along the top edge. Reading through other posts it seems like this shouldn’t affect anything, but until I get a successful calibration it does make me wonder. I am watching a few tutorials on the calibration process, so it’s probably me, but still wondering about getting a backup calibration plate.

Thanks!