I first tried to bleed the old one with no luck. I then took all of the hoses apart and the plunger appeared to be cocked sideways. After fixing that and bleeding, it seems to be working.

I'll box up the untouched replacement and send it.

The one I tore apart had the fluid changed within a few days of failing. So I completely agree that changing the fluid is definitely not the cure.

BTW be careful when removing the spring loaded quick connect fitting. I was lucky to find all of the pieces when it went flying across the garage.