Hello @Zbyszko, you don't provide any details of your settings so I have to guess that it is underextrusion following a long travel. To cure that, set combing mode to no skin and the max distance without retract to 10. Hope this helps.
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HI Guys, sorry about the lack of detail in my OP... it was getting late. I have a Monoprice Maker Select 3D v2. The print was in ABS with which I've printed a bunch of other items, most taller than this, and they came out fine as long as there was no bridging. This seems to be related to what smartavionics posted. I'll try your suggestion today. My settings were:
Combing mode: within infill
Retraction distance: 0.5mm
Retraction minimum travel: 0.8mm
Layer height: 0.2mm
Line width: 0.4mm
Infill line width: 0.4mm
Wall thickness: 1mm
Coasting: off
Playing the layers in Cura it does look like there are some hops going on (see screenshot) when its printing the motor holders. 
Applying the settings to set combing mode to "no skin" and extending the no retract distance to 10mm:
I'll give this a shot this evening. Let me know if you have any other input based on the additional info I provided (or if you need any more info for that matter). Much thanks!
On 3/10/2019 at 3:18 AM, smartavionics said:Hello @Zbyszko, you don't provide any details of your settings so I have to guess that it is underextrusion following a long travel. To cure that, set combing mode to no skin and the max distance without retract to 10. Hope this helps.
Tried these changes but the print came out pretty much the same.
It also reminded me that I had this issue when trying to print small washers (another circular part) for my 3d printer bed. I have them around still so I went ahead and re-sliced them with the other app to see if they print correctly (something I did not originally try), and they did. I checked the speed and they printed at around the same rate as per repetier host viewing of g-code. The Cura-sliced ones washer were printed at 245C so a little higher but the frames above were all at the same temp (240oC). The ones on the left were sliced in Cura 3.6 and the right were in Slic3r and printed today. 
Convinced that this is some setting to do with either circles or thin parts, or both, since all my other Cura-sliced prints without these features printed fine. I've attached the g-code from both; perhaps you guys could take a gander. Much thanks.
Edited by ZbyszkoThree obvious differences in the gcode are the the Cura sliced parts are not using any cooling fan, the walls are being printed faster than the Slic3r sliced parts and you are printing fewer parts. All of these things will tend to cause the parts to overheat.
Thanks again for taking the time to reply. The Cura g-code I believe was my second attempt at printing the washers because I recall the first time I tired I tried printing 6 at one time. I've added an 8 second minimum layer time to my Cura settings but maybe I need to bump that up further and test.... Most advise not to use cooling fan when printing with ABS. Wall speed is auto-calculated to 1/2 of print speed but maybe I'll override that to something like 1/3 and see how it goes. Will retry and post results. Thank you.
OK, I just printed another couple of the washers along with some hubs that I needed to print. I slowed the print speed in CURA down to 35mm/s which made the wall speed 17.5mm/s. Min layer time set to 10s and lowered the print temp down to 240oC. You can see that the issue is still persists on the washers (back right) where it looks like it's printing in spurts. When I look at in Cura layer view it shows that the entirety of that section should be a shell and it basically makes one rotation clockwise/counter-clockwise at 17.5mm/s then reverses direction before moving onto the next part. I'm stumped!
This has nothing to do with fan speed but I do recommend a *little* bit of fan for ABS. I'd do the minimum fan. 240C seems a bit too cold for ABS.
Anyway I don't know what your problem is - clearly it's major underextrusion but I don't know why.
Have you tried printing this in PLA? Then you know if it is related to the material, or to the model/slicing?
Or else, design a couple of test pieces, with only the faulty parts, plus a dummy block to provide enough cooling time per layer.
In some of those test pieces, model them as shown here, as separate models. In the other test pieces, do connect both edges of the openings with a thin plate to each other. So the printer does not have to stop printing, and does not retract, but can keep going. Then you would have this sequence: dummy block --- connection to the test piece --- test piece itself --- connection to the next test piece --- test piece itself --- connection back to the dummy block. So, no gaps, no retractions (theoretically and hopefully).
I just downloaded Cura 4.0 so was going to try printing with a "clean slate", however it seems that it copied over my v3.6 settings since I didn't delete that version before installing the new one. Going to try and do a complete re-install over the weekend and see how it goes. I'm pretty sure this has to be a settings related or Cura-playing-nice with printer issue since as you can see in my earlier post it prints fine using a different slicer with same material.
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gr5 2,172
Well it's basic underextrusion on the higher layers. So what's different starting around 2mm above the bed? I don't know. Typically Cura cranks up the fan and also the speed slowly over several layers. It could be that you are printing too fast on the upper layers but cura is printing slower on the lower few layers (which is default).
What kind of printer do you have?
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