I'm rebuilding my C-6 using a Bad Shoe/Broader/ factory shop manual method.
I'm to the point where I'm doing the air checks and everything is good except the servo, which leaks and does not move at all when I hit it with air.
I had the "newer" style one piece servo in there first and then I rebuilt my old style servo and the results are the same. The air seems to be blowing out of the hole the servo shaft rides in.
The servo pin case bore might be worn. Try the piston in the case without the servo cover and see if the pin is loose in the bore. If it's ok, lub up good and reassemble being sure the servo moves good in the servo cover. Be sure your air blower has a good seal at the port and blow with full air pressure and it should work.
Ken Collins, BadShoe Productions, How To DVD's specializing in Ford drivetrains www.badshoeproductions.com (banner ad below)
Thanks Ken! I tried a third servo and it sort of moved. I then found your You Tube video on air testing a C-4 and realized I need to hit that servo with some AIR!!
I was babying it at 25-30 PSI. 50-60 PSI makes the good servo pop the band in a hurry.
I learned that a lower pressure works fine for other air checks, but I guess the spring in the servo demands more pressure to make it move.
Your video is has been a huge help!