Do you have a tension meter in your kit near the screen print machine? This really should be the number one issue, dropping screen tension. In the glass industry, I bet this would hold to be one of the top, if not the top issue on the list. Reason is, we screen print the same product for long periods of time and have set up our machines to work with that product and specific screens for long periods of time. Most screen printers; for plastics, fabrics, etc, have to deal with differing inks all the time. They are used to tooling the machine to work for the ink or desired output. Know what the recommended screen tension is for your screens? If you don’t you gotta find out. It’s the difference between quality repeated prints and streaks, lines, and light/dark spots.