Brake booster itself gone bad, or check valve?
Curious if one is more prone to failure than the other? I know the check valve is only about $6 with grommets so I can try that first. But the past month, every time I go out to start the Jeep, the brakes are ROCK hard. It's like the vacuum reservoir is leaking all of the vacuum out and causing the problem. This also happens about 2 hours after shutting the Jeep off. Doesn't cause drive-ability issues but I want to get this fixed before it gets bad and causes an accident.