Printing problems

thingiverse

Hi fellow 3D printing enthusiasts! I'm stumped by a problem that's got me scratching my head - hopefully someone out there can shed some light on it. I designed a detailed model in 123D Design, exported it as an STL file with "fine" settings, and then imported it into Simplify3D to start printing. However, after approximately 7 mm of printing height, I noticed that the layers were weak and couldn't figure out why this was happening. I tried printing a similar model two weeks ago, but it exhibited the same symptoms. My printer is a Vertex 8402, and I've been running this project with black ABS at a temperature around 230 degrees Celsius, moving at a speed of 2400 mm/min. Take a look at the images below to see if you can identify what might be causing the issue - I'm truly grateful to anyone who can help me solve this mystery.