During the build the movement ran fine, seconds hand ticking normally.
Issue: after assembly it would only run for 10-30 seconds before stopping. I wore it for about an hour and manually wound it, feeling slight resistance (-80 turns) but it kept stopping after a few seconds.
Left it for 2 days and now when I wind it with the crown I can feel resistance but the seconds hand doesn't move at all.
The rotor spins freely when I move the watch (visible through exhibition caseback). The crown is fully seated and screwed down correctly.
Questions:
Is this a mainspring issue, could it have been damaged during assembly? Not unlikely given it was my first build and I was making mistakes constantly.
Could the crown stem trimming I did have caused any issues?
Is the movement salvageable or do I need a replacement NH38A?
Any other diagnosis steps before I give up on this movement?
For context: the movement came from AliX listed as genuine Japan NH38A, 1000+ sold, 4.8 stars.