So, out of the box the MP Select Mini has a problem with the hot bed wiring. The way it sits inside the printer, it rubs against things, and the zip ties pinch the cable. After a while, all MPSMs end up with a broken hot bed.
The solution is to route the wires outside of the machine, which might involve drilling, if I didn't have the ability to print a new side-plate myself.
This one came in two parts (the left side was part of an earlier project for better cooling, the right was a modified file from that project, for the cable routing), and the first piece I printed (the right side) obviously suffered some warping during the print, so I'll have to re-print it later.
Waiting on a braided sleeve coming from Amazon early next week, and I need to pick up another rubber grommet (was able to repurpose one of the ones I needed from the no longer used hole the wires used to go through), so I'll re-print it before then, since it'll have to come apart anyways.
At least now I can safely use the thing without worrying.
The warping was most likely a heat issue. With the PLA a higher heat for the first layer is good for adhesion, but if it's too hot for too long it seems to start warping. The trick is to lower the temperature to around 35C after the first layer or so is down, and it seems to be fine, as you can see with the left piece.
Once I re-print the warped piece, I can glue them together and wont' need to use duct tape to hold it down.