QTR-Quadtone RIP

I have been testing QTR for sometime now, on and off, and have
generally been very pleased with the tonality and quality of the
results. Unfortunately there is one problem that continues to
disappoint me and however hard I try and with all the possible
combinations I can think of, I have been unable to solve the problem.
I am using the Epson 2400, nozzles and alignment perfect, Windows XP Pro.
The problem is that I have very fine horizontal banding/white lines
(which are just noticeable to the naked eye) at the beginning and end
of the printed area, being between 1 and 2 cms deep and the full width
of an A4 or similar size page (I have not tested this with larger
prints).This problem is not detectable in any other part of the print
such as shadow areas.
I have now updated to V.2.5.0.3 and re-printed the file( Tiff, QTR
GrayLab) with my preferred settings:- Paper size as original and 100%
scaling, Sheet Feed, Matte, UCmk-EnhMatte curves 1 & 2, 1440x1440
super, Bi-directional, Ordered, but no change.Using any other matte
paper gives the same result.
Previously any combination of settings I may have used have not
eliminated the problem (and I think I tried them all, even thinking
drag and drop or select from File might make a difference!!).
For this new version I have not tested changing the resolution, speed,
or dithering as I am sure I will only repeat the problem at the cost
of ink, paper and time.
However, recently (this weekend) I printed an image area within an A4
leaving a white border of 3cms and this did not reproduce the banding!
A positive result finally, but one I am not prepared to use as a
compromise.
Possibly the one setting I have not tried is the manual front feed.
I am, however, able to print perfectly with ABW or with ICC profiles
through Photoshop.
I have yet to attempt to build my own profiles/curves with my Xrite
Pulse but at the moment this will be new ground for me and I would
really like to resolve this issue first.
I would really appreciate some help here.
Many thanks in advance,
Philip