Steve,
The 4 things I would do, and in this order:
1. Clean your stencil with stencil cleaner wipes after it comes out of the stencil cleaner. I like MicroCare ProClean (MCC-PROWR). I will even saturate the wipe with a bit of isopropal just till the wipe is damp, at least on the 1st pass. I wipe the bottom vigorously for 20-30 swipes forcing the solvent up through the apertures, then wipe the top once from left to right. If the wipe has any "dark" material at all on it i repeat the process till it does not. The stencil must be absolutely clean for these types of parts. Trusting in your wash blindly will not cut it.
2. Make sure your paste is fresh. It is not usually a problem this time of the year, but I don't know where you are at, so it bears mentioning. I have seen good paste added to dried out paste in an effort to "save" money. Now we are throwing out 2 jars of paste instead of one. If paste is dried out, toss it. Reliability of your circuit cards is greater than the cost of a jar of paste.
3. Environmental conditions. Temperature and humidity, at least inside of the screen printer, can affect print quality. Read the TDS for whichever paste you use. Meet or exceed the recommendations.
4. Nano coatings. If you need them, then you need them. You should at a minimum be using quality stencil squeegee blades that are coated. This is such an easy thing to do, and it makes a small difference. Sometimes a small difference is all you need to make an iffy print into a good print. I like Permalex blades from Transition Automation. There may be others that are better, i wouldn't know. These guys product is so good I haven't bothered to shop around. Replace them as suggested. I think they recommend 6 months under heavy use, and 1 year under normal use. They will call and make sure you are happy, and remind you when it is time to replace them.
4.
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