Top of print lacks fill

Hi,I designed a filament guide for the top of an 8mm acrylic I3.
The bottom 7/8th of the print is fine,but the top part is seriously deficient,with incomplete infill and perimeters.
What could cause a problem like this?Slicing?(Slic3r)
The printer is an Aurora I3,fitted with a Wade's extruder,J-head hotend (genuine hotends.com) with 0.4mm nozzle.
Printed in 1.75 PLA at 185 degrees hotend,50 degrees bed,blue tape on aluminium bed plate.
Ramps 1.4 electronics running Marlin.
Just for the record,here is the STL file:[www.thingiverse.com].

Btw.,I calibrated the extruder recently,which supposedly set the feed correctly.

Edited 1 time(s). Last edit at 09/24/2016 01:57AM by clogs51.

It's a small part and doesn't have time to cool before the extruder tries to put more plastic down on top of the still-hot previous layers. Print multiple copies or a sacrificial part to give the extruder something to do while the print cools.

If you have a print cooling fan make sure it is running.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I forget if slic3r has a layer change code section, but you can tell the extruder to go to 0,0 and do a wait command for a few seconds to give the print time to cool inbetween layers

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If you need some help, or don't understand what I just said, feel free to send me a PM anytime

Printer: Prusa i3, 2 E3D v6 Hotends, Arduino + RAMPS 1.4 with a Bypassed 5V Regulator, 400w Insignia ATX PSU, Custom Designed Bowden Extruders