Grayco spray pattern problem

I've got a grayco airless sprayer, the 900 series magnum, and it seems to not spray right. I've tried a couple of new tips, and had the pressure from low to high. What i'm getting is a good spray pattern the width it should be, but then a gap and a stripe on each side of the pattern. I'm at my wits end, i've had close to a hundred gallons of different brands of paint through this thing in the year and a half i've had it and it worked great until the last 25 gallons or so. I'm beginning to wonder if there's anyway the nozzle itself (where the tip goes in) could affect the pattern.
thanks
steve
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Are you sure they are new tips, is there any way the pack could have been opened and resealed, because after spraying myself 3-400 gallons with my titan thats what it sounds like. You can blow out a tip fast with higher pressure, in less than 1 hr with some product. Grayco would know more.
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On Tue, 28 Apr 2009 04:44:01 -0700 (PDT), ransley

Anything change in the last 25 gallons? Not mixed well, strained well or *buggers* in the paint. Change in viscosity or such?
"New tips" the same size and number....
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Damn, Steve, I hate to write the following, but it's just what I'd do from my experiences with a Graco. I know you're a knowledgeable experienced person, but you're missing SOMETHING.
On my Graco, I can turn the spray nozzle 180 so the big end is out, and if there's anything in there, one spray, and it is gone. What you describe is something getting in the nozzle, blocking it partially. That would mean you don't have a sock on your intake, or your paint has a lot of chips in it, or your pump has a lot of "stuff" in it. I thought I had cleaned mine adequately, and put the Graco stuff in there inbetween batches, etc, etc, etc. Then one day it just wouldn't work. I took the pump apart, and was amazed at how much stuff had solidified in there in just a short time.
First thing I'd do is run water through it real good. Clean out everything you can get to. Then I'd try it with a fine mesh screen over the intake. Maybe even strain the entire amount of paint, altho that would be a PITA with thick paint.
After that, maybe it's time to take it apart, and clean it thoroughly, pump and all.
But I'd try the water and fine sock tricks first.
Let us know what it was when you find out.
The other Steve B.
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SteveB wrote:

thanks for the replys. I've covered about everything i can think of except taking the pump apart. I don't think it's getting stuff in the tip. The lines were there from the very first squeeze on a (yes) brand new tip. I did, however, buy a tip that was really too small because they were out of the one i really needed. I've been pushing KILZ brand (pretty darn thick) bright white interior semigloss through a 415 tip. TODAY we purchased a new 619 tip and a new guard. I'll try them out in the morning with a new bucket of paint. We'll see. Basically all i'm using it for is popcorn ceilings in rental rehabs, so the lines are not the end of the world, it just doesn't make sense. We also usually paint the interior window trim at the same time, then the rest of the wall painting is done with rollers. I'll report back this time tomorrow.
thanks again for the suggestions.
steve
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<snip>
Can't help but wonder if the paint formulation has changed to something abrasive. Silica pigments are much more so than calcium carbonate, for example. This could selectively etch away the tip material in use and screw up the pattern. The effect could be a problem later in unusual pump wear.
Joe
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