Solved ABS printing problem

Here is a new question for the guru in the group. I have been printing mostly ABS and mostly smaller items with no problems. I recently started working on a statue of Vinus de Milo and have started having problems. What is appearing to happen is the print job starts and prints the first 2 layers, then the next 3 layers are more or less like the air layer on a raft (raft is turned off) then it continues with the build on to the top of the part (about 270 layers). Layers 3 through 5 just don't appear to be sticking to each other very well. Any thoughts or suggestions? What other info do you need to try and help figure this out. Additionally, when I do print a raft, the raft and the bottom layer of the part do not have the air gap printed at all which makes it almost impossible to remove the raft.
I am using Mattercontrol v1.4, 237C with a bed temp of 90C. Inside perimeter speed is 40mm/s and outside perimeter is 50mm/s.

Thanks
John

 

Does this error show up in the g-code preview? Is the filament jamming at all?

 

Thanks for the reply Mike. There are no jams or clogs, that was one of the first things I checked for. During the past three weeks, I have been looking at almost any and every thing I could think of that could cause the problem, with no improvement. I finally threw in the towel and sent a request to Robo3D Tech Support. I got a reply back yesterday with some info about the Z offset settings, but that was not the problem. Last night I pulled the bottom off the printer again and rechecked the ramp board fan, and it was running and clear. On a fluke, I swapped the fan with another one I had (same specs) and restarted the process again. The first print was perfect. Apparently, the fan had started to fail and was not blowing enough cooling air over the ramps board (the only thing I can figure out) as that is the only thing that has changed that has made any difference in the performance. T am going to look into a fan with a larger CFM output as a replacement or some other cooling arrangement. Apparently, the ramps are very touchy about heat, or lack there of. Thanks again.