MNM mk1 track button not working

I got a new MNM mk1 in the mail and the owner said it was in perfect condition, not packed super well, etc… It was freezing at the start up screen & while editing which seems to have resolved with factory reset. Step 13, Track 1, and track 5 wouldn’t work at all. I tried to clean them, used compressed air, and contact cleaner. Now step 13 & track 1 work perfectly. The track 5 button presses down without issue. I took off the faceplate, cleaned everything as best I could, wiggled it, but it has never yet selected. I booted in test mode and the machine shows response from all buttons except track 5.

Any suggestions for troubleshooting it before I send it back? I assume it’s probably a contact issue that happened with shipping and would require maintenance with soldering or something? I got it cheap (600$) so would be sad to return it. I’ve read a lot about the freezing and button issues on these forums and am picking up a MD mk2 uw this weekend, but now am getting worried. Are they buggy or is it just online gripes vs. happy musicians who don’t go online to say how stable they are?