Introduce Spraying Polyurethane Troubleshooting

We got a troubleshooting question for you. If you're spraying one or 2K polyurethanes, so I am very familiar with using a siphon feed cup. I use it all the time. I spray one or 2K polyurethanes. But if you're spraying one and 2K polyurethanes and you're having a problem doing the same thing, if they called you up, John, got you on the phone, what would be maybe one of the solutions to that problem?