Screens not exposing!!

Are you mixing in the diazo?
What kind of exposure unit do you have? age?
Where/how are you storing your screens when drying?
Are you using plastisol on the jobs that break down the screen?

What is fastlink? Who makes it? If the screen is breaking down it is either underexposed or the wrong chemistry for the ink. If the screen is one of those that is almost impossible to spray out then they are being pre-exposed to UV light somewhere. So you've changed locations and emulsion right? Is there anything else that you've changed or that is different from when you were having no problems?

squeegee pressure?

I think this is a product offered by Screen Process Of Alabama. I had a hard time with it also. But they sell a bunch of it. The bottom line was I needed something a little more forgiving. I'm not trying to set any speed records burning screens but for larger shops it can be a real time saver if you can shoot screens in under a minute. But give those guys a call at SPA they are good folks and could point in the right direction. They might get you in touch with someone using it with the same equipment that could help. The good news is you can always go back to what you were doing before. ( that stuff is way sensitive to any UV light, you can over or under exspose real fast. best of luck.)

What does squeegee pressure have to do with developing the screen?

Bulb might have gone bad it sounds like then.

Another possible issue is emulsion was sensitized too long ago and stopped working properly.