Shortly after I posted about my weird first layer issue the z axis motor failed completely. It is an oddball cheap motor and I could not find a direct replacement. The screw was also a very small diameter piece of all thread. I replaced the motor with a standard nema motor with a printed bracket. I did have to do some surgery with a Dremel and drill in order to get the new nut mounted to the carrier. I also had to change the steps per mm in firmware for the new screw. I haven't changed any of the slicer settings just different filament which is stringing pretty badly and I think the printer is going a bit fast. Other than that it's running pretty good.

Ah, Monoprice. I have a couple of their models. I think they're great for the price. The two I have are larger than this one. However, I really want to upgrade to a Prusa. Auto leveling, a magnetic bed that doesn't fall apart after a print or two, multiple filaments. Have fun. Print mods. Go crazy with it.

I have that same printer and I've got similar issues, although it gets worse as it climbs instead of on the first layer. I wonder if it's the motor going out.

Here is the guide I used

https://hackaday.io/project/14823-monoprice-select-mini-maximum-3d-printer-mods/log/55525-upgrade-the-z-axis-with-a-nema17-stepper-and-tr8x8-leadscrew/

I had to cut out the old lead nut and drill tiny holes to mount it. The wiring that came with the new motor plugged into the main board but the motor turned the wrong way so I had to switch two wires. Do not switch them the way they did it in the guide it will not work.

Something to consider is also that the stock screw is not standard and you should change your layer height to

Layer Height (mm)
0.04375 (results may vary)*
0.0875
0.13125
0.175
0.21875
0.2625
0.30625

https://3dprinting.stackexchange.com/questions/3904/what-are-the-magic-numbers-on-a-monoprice-select-mini

Awesome, thanks!