I've got a small 12V DC .9 Watt 'muffin' fan (1.75"x1.75"x3/8"). It was the cooler for a video card's processor chip and was frozen up.
I put a drop of oil into its sleeve bearing and it now runs reliably - almost. It will start every time as long as it is not oriented with the open 'face' down. (The open face is the side in which you can see the bearing). If the open bearing is down, it sometimes starts and sometimes needs a slight nudge to get it going.
What's going on? How come? TIA