I'm new to posting solutions but I struggled through this and the solution was simple. Thought I would share with others. My 2007 Nimbus 336 slides went from working perfectly to the yellow light taking a long time to go solid to the blinking light never going solid. I replaced both manifold Vacuum switches RAP93072 and problem still existed. I then removed the poly bowl and found corrosion from the brass clogging the Bottom fitting of the check valve / pressure sensor. Cleaned it out and everything works perfectly. This was a battle all summer to the point I couldn't retract my slide on a trip and was stuck for hours before it finally came in. I attached pictures and others can email me if they have questions. I attached a picture of the bowl.