Digital BW, The Print

Hi, all!  I've been lurking around for a while, this is my second post.

What position do you set the paper thickness lever (plain paper or 
thicker media (indicated by an envelope sign)) on your Epson 2100/2200 
when printing on Epson Enhanced matte (aka Archival matte)? On my 
printer I get smearing at the right top corner at the plain paper 
position, which goes away if I raise it to the "envelope setting. Is 
that a common setting for this type of paper - after all it is not a 
particularily thick and heavy mediûm! 

A little background to the question. I get a smearing on enhanced 
matte in the right upper corner if I leave the lever at the plain 
paper setting. The smearing disappears if I change lever to the 
envelope position. (Incidentally, I get less but still some smearing 
even on plain inkjet paper.) I thought that this indicated that I 
should do the moist paper towel cleaning routine.  I did two cleaning 
cycles with the paper towel, and there was indeed quite a mess on the 
paper towel after that (but is hard to say, how much of it was really 
the mess accumulated on the print head and how much a result of ink 
seeping normally through the nozzles). However, even after this 
cleaning, I still get the smearing. I thought that I should do another 
couple of rounds of paper towel cleaning, but then I tryed (for the 
first time), printing on a bigger size a3+ paper, and I could really 
hear the printing head hitting the paper. So this leads me to think 
that perhaps my print head is not particularily dirty, but either 

a) for this type of paper one should normally use thicker media lever 
setting

or

b) my printer is seriously misaligned and the printing head is lower 
that it should be.