So last night while I was printing a few small things, I noticed that the print head was actually moving slightly on its platform.  The 2 vertical screws that hold the horizontal "tail piece" to the main/front sliding block were loose and the entire head assembly was wobbly because of it.  But when I removed the screws to get to the 2 loose ones, I realized that the wood piece that holds the hot end in place was also very loose, so I had to disassemble the print head.

When I took off the screws that hold the extruder to the motor, 3 or 4 pieces of the plexiglass layers came off.  These were the right corner pieces that have hold the wood platform screw in place and they had broken off.  Only one plexi layer was still intact.  I glued the pieces back, and also glued the back 3 layers together and the front 3 layers together, so they're stronger now, but I think I'll be printing a different print head to replace this one.

Anyway, after I got everything together, I printed a test print, and as far as I can tell, the banding is gone.

All things considered, I think that Solidoodle should reconsider the design of the print head from a more structural angle.  Yeah, it looks cool being transparent, but it has a lot of weak areas that are under stress, so they're likely to break sooner or later.  Or at least they should glue some of these layers together to give them strength.  The way it was designed, you don't need all the parts separate, the back 3 layers can be glued together, and the front three can be glued together, then everything can be assembled together with the captive screws in place.