Below is a good example of a leaky headlight vacuum motor. When I first purchased the car, the vacuum system would keep the headlight doors closed overnight. Over the years, the performance deteriorated to the point where the doors would only stay shut for about 2 minutes after the engine was shut off. You could hear the vacuum leak quite clearly. Part of the problem was solved by replacing all of the vacuum lines related to the headlight motors – this boosted the time to about 10 to 15 minutes. The majority of the leak was in the two motors themselves. You can see in the photo below (arrow) that the rubber shroud at the top of the vacuum motor is collapsed on itself. This photo was taken with the engine running and this is a sure sign that the vacuum motors need to be replaced. I replaced both of mine and now the system keeps the doors shut for about 5 hours with the engine off. There are likely some other more minor leaks in the system, but this is good enough for now.
I have read elsewhere that some people have had difficulty in removing the vacuum motors and in some cases have had to take apart most of the front end of the car in order to get the motors out. For both motors (and in fact I’ve had the motors out twice each) I was able to manipulate the motors out (and the new ones back in) without removing anything more than the horn – which you can just see in the upper left-center portion of this photo. With the horn removed, it is possible to twist the motor towards the outside of the car (top of the photo for this right-hand motor) and wedge it out. There will be considerable resistance, but it is possible to get in and out. This is contrary to the 1969 Ford shop manual, which indicates that you can lower the motor out through the bottom. Though the bolts holding them in place are accessed from underneath, there was certainly no option for removing the motors themselves from the bottom on my T-Bird!
I purchased my rebuilt headlight vacuum motors from the T-Bird Sanctuary in Oregon (1-800-275-2661 for orders or 503-692-9848 for other enquiries). The cost in 2001 was $85 per motor with an additional $35 core deposit. You have 30 days to return the old motors without the core deposit charge being assessed against your credit card.