I'm having a problem with spots appearing on my plate during make-ready or a run. I can't figure it out. I thought it might be a bad batch of chemicals or plates, but they've all been changed and I'm still having this issue. I have a DPM2340 from Presstek. It's about four years old but very well maintained. I only use their chemicals and plates (8mil poly). My exposure is correct according to the output plate. You do not see the spots on the plate when it is made and you can remove them with deletion fluid after they appear, but obviously that's not always an option depending on where they show up. It almost seems like it's powder or paper dust as it sometimes happens to both plates in the same place. The spots are various sizes and don't appear in the same place every time. It's completely random. I thought about recalibrating it but my densitometer doesn't read in screen percentages and I don't know the math to convert it.