I pulled the Pump and took a close look at the aneroid valve. The balder has pin holes in it. It was damaged at the bottom near where the corrosion had been when I unstuck the valve a year earlier. I remember now thinking "I should change this bladder because it looks weak where it was in contact with the area of corrosion". But, I was behind with a job and pressed on. The truck was doing much better and although I could see a mare, I could not see any holes in the diaphragm. So, if you let your truck sit too long moisture can get in the aneroid valve and stick the valve and damage the bladder.
Thanks for all the help.