Winds, doesn't run

I have one of the skeleton models with a Miyota movement, about 2.5yrs old. Last week I set it down for more than a day since I wasn’t wearing it. When I grabbed it again and wound it…it didn’t run. Looks like the winding is fine (i can see parts moving and it feels the same as before) but nothing moves after it’s wound.

Any suggestions how I should try to troubleshoot? I’m not familiar with watch parts beyond the few things that needed to be manipulated during assembly (like the release for the stem).

Can you set the time? I.e. can the hands move smoothly and without contact?
If you open the case, look it over carefully with the loupe. Are all the gears clear of debris? Something as small as an eyelash can gum it up.
If you VERY VERY VERY carefully press the pallet fork, do you feel any resistance or pressure? The goal here is to manually cycle the hair spring one tick.

Thank you for replying.

Yes, the hands move freely and smoothly. I will open up the case and take a look, but I don’t know what the pallet fork or hair spring are! Can you explain/send a picture? Or should I just ask Google?

The forum doesn’t let me upload photos. This youtube should direct you to the right location:

Basically, you’re going to see a bunch of gears – gears are fine. You can safely touch gears.
You will see a brass circle with a super thin spring wrapped around it. That is your balance. DO NOT TOUCH THE SPRING.
Engaging the brass circle to a weird-shaped gear is a tiny piece with two purple tips. That is the pallet fork. You can GENTLY nudge the pallet fork. It swings left and right a short distance. So it will be at the end of one of those swings. Since it should be spring-loaded, a VERY slight touch should push it to the other end of the swing. That’s one tick.

Since it’s a skeleton, you should have visibility basically everywhere. Just TAKE YOUR TIME. This should be a restful, thoughtful activity. Go over it slowly with your magnifier, watching for something stuck between gears. Since you can manually engage the hands, you can probably skip all the gears you see moving when you do that. Just focus on the gears that do not move.

Other watch construction rules apply. You’ll be wearing gloves or finger cots. You will hold the movement by the outside circumference. You are manipulating pieces with your pegwood and tweezers. You’re working in a clean location. This includes the floor, lest you find yourself on hands and knees searching for a teeny piece lost in a fluff of cat hair. You’re taking your time. At this skill level, you are NOT disassembling the movement. This is a little stressful, but worst case you can replace the movement for ~$50. No matter the result, you will be better at watch repair because of it.

(Yes, I’ve been down this path before. Can you guess what I touched? Can you guess what I bought? :wink: )