Over Extruded Layer?

I have an Ord bot and have been trying out a new extruder design using a geared Nema 11 stepper. I'm still dialing it in. I thought I had it working well, but had problems when I let it do an overnight print. I printed a dodecahedron and noticed a layer close to the top looked overextruded, since it was protruding all the way around the print. Has anyone experienced this type of issue? I still have some issues with ridges on the perimeter edges too though. My xyz (all belts) acceleration is 650 mm/s^2 and my extruder acceleration is 800 mm/s^2. Jerk for xyz is set to 10. Print and infill speed were 25 mm/s at 195 C and 0.3mm layer height. Here are some pics:

To me it looks like your z heigth skipped at that point. Hard to tell from the picture.

That's what I was kind of wondering. My z-axis is belt driven and I currently its settings set the same as x and y. I also have the z-axis always enabled in firmware to prevent my carriage from dropping during the print. What can you do to prevent skipped steps for the z-axis, particularly when it's belt driven?

Because your print ran for a long time before it happened, I can only think of acouple things. Binding at that point, stepper motor overheating, or maybe stepper driver over heating. Or it could just be one of those one off problems that never happens agian. I would run some other prints before you start tweeking too much. You may end chasing ghosts.

Maybe try counter balancing the X axis weight.
Extend the top Z axis pulley, wrap some string around the pulley with some lead fishing sinkers hanging on the tag end.

That's actually my current setup right now. The x-axis is counterbalanced with 2 lbs of sinkers. I have a [www.thingiverse.com] page on the z-axs screw conversion for anyone interested. But, still trying to work the bugs out. My y-axis seems much nosier than my x-axis and I'm not sure why and if that has anything to do with any of my problems? Getting the geared nema 11 dialed in is also an issue. I was using a PG35l motor but noticed I had great layers and no retraction with it at 1200 mm/s^2 acceleration, but then I noticed when I lowered it to 400 mm/s^2 acceleration I got retraction but had crappy layers. Hence why I'm trying out the geared nema 11. So many little things.