Digital BW, The Print

I have posted this on the piezo board but was hoping a broader 
audience might help me resolve the problem.
I am using a 2200, Sepia K7, QTR w/supplied curves, win XP
I have seen this problem on different papers and different profiles. 
The only pattern I might be able to note is the more texture, the 
more noticeable the splotches. Also, the thinner papers seem to 
exhibit the splotches even more than their thicker relatives.
Here's a scan of what I am seeing
http://tinyurl.com/2efpz6
Up to about 25% the gradient is smooth. Then the noticeable 
splotches come in. This scan is from innova fibaprint which really 
showed off this problem. Looking at the ink curves, at ~25% the 
magenta shade comes in. Well I put a new cartridge in to see if that 
would help, no. I did the windex thing at the capping station, 3 
head cleanings in a row and insure all cartridges had their air 
vents open...still get the splotches.  
What else could cause this problem and why does it vary with 
different papers?  I was printing the recommended 2880 and wonder if 
that is why the thinner papers exhibited this moreso. Opening the 
lid, I could see the ink sitting on top of the thinner papers, so I 
think the profiles were meant for the ~300 wt papers. However, I 
still see the splotches on the heavier papers.
Any suggestions?
I was considering soaking the cap station in windex and slidign the 
heads over it for a day or two...
thanks for any help
Scott