Printmaster PM52-4 powder issues

[MarkyMark]

We are running 8 pt. C1S stock, 4/0. We've been running this product successfully for years. Started having quality issues with previous stock (Productolith Points) and we are trying Billerud Crown Prestige C1S. First day's production offset terribly. We had also printed a bunch of 80# Lynx uncoated that day, with no issues. When we examined the printed C1S sheets more closely, we found there were parts of the stack that were not offset, and were OK to sell. When wiping by hand the parts of the stack that were offset we could not feel any anti-offset powder. We tried printing a form with very heavy dark coverage on the Crown Prestige just as a test, and it did not offset. We are awaiting delivery of another brand of C1S (Kallima) so we can do a side-by-side test. We are concerned that we are having a sporadic issue with powder unit. Powder is being consumed and we can feel that the pump is sucking in air.
So,
We are having no offsetting issues with 4-color printing on 80# Lynx uncoated,
We are having sporadic offsetting issues with the Crown Prestige C1S.
Press is Printmaster PM52-4 (2005). Powder sprayer is Mediprint T-Tech GS30-T. Powder is OxyDry Oxy36 (not coated, 35-40 micron).
There is no visual or audible sign that the powder unit is working--no flashing light, no audible click of a solenoid, etc.--except powder is being consumed.
Where should we be looking?

 

[Jack liston]

Clean powder unit thoroughly.print a small batch dry solid black sheets . use black sheets to see spray pattern from powder unit to see if enough powder is getting to sheets.if not adjust gap . Also make sure you're cmyk build is not over 275 Total

 

[MarkyMark]

Thanks, I'll try that.