79 continental headlight doors open when engine off

I have a 79 continental with headlamp doors that won't stay closed anymore when the engine is off. When its running, the doors close, but won't stay closed when the engine is off. They used to stay closed all the time, then I would notice that they would be open about once every two weeks, on and off. Then gradually they would be open in shorter periods until now when they open almost as soon as you turn off the car.

Anybody know whats going on? A vacuum leak somewhere?

I'm going to guess the large "coffee can" vacuum reservoir is leaking.
May as well check the coffee can hoses as well.

yep vacuum leak somewhere. could be anywhere in the vacuum system including the coffee cans. but check all you're hundreds of vacuum lines