Prints become airy very fast?

I am currently working on a MakerBot with Sailfish 7.7 for a company that I am interning for, and am having some serious issues.
As I print, after a few millimeters of Z axis printing, the prints become very airy/filament stops being extruded. Before this happens, the prints are great. After a few layers, it begins to deteriorate until it stops working all together. If I unload the filament, cut off the melted bit, I can load it back in without any issues. I can then repeat the print, and have the same issue. I have tried multiple prints of various objects, all are the same. When I look at the filament I pulled out, I can tell the extruder gear ate out a nice portion of it. If I try to force it (When it no longer is extruding) no matter how hard I push nothing really comes out. I would want to think its a clogged nozzle, but how come I can fix it without having to clean it?
I used MatterControl as my slicer
Print at about 40mm/s, with 225-230C (Tried with both)
Don't think its the build plate either, as the first few layers are the best.
I can upload an image if needed.

ABS? PLA? Gruyere cheese?

- Tim

Sorry, PLA. Should have mentioned it is a Rep 2. The Filament is Makerbot's own True Color. Tried with a different, new role, still same issue. Cleaning it now. Is it bad that the metal tube that goes into the hotend/nozzle has a few nicks on the inside? sliding filament back and forth in it, I realize it kinda almost catches. Could that be sufficient enough to cause such an issue?

225-230 too hot for PLA? I print PLA at 195 at 30mm.

The default for MakerBot is 230... But yea, I do think it is kinda hot. Thing is, I had this great print going at 210, and at the last 10%, it failed, for the same reason. Also, at this temp (and lower) the PLA stops sticking to the rest of itself, and so it comes out more as strings.
Speaking of which, how come the tops and bottoms (Horizontal surface prints) come out with a lot of spacing? By this, I mean that instead of it coming out as a nice smooth surface, there is a gap between every line placed by the extruder. I would want to think its because its underfed/not enough filament being extruded, but I haven't adjusted that yet... And the walls/raft comes out perfectly fine.
After I finish cleaning this all, I can try again at 200C, and see how that turns out... But I can imagine it probably won't even stick to the blue painters tape.

Watch reported temp. If the temp is staying the same but the filamet gets airy and the bolt chews the filament, you may have the same issue I am having. I have replacement thermistors on order. My I3V does the same after long prints and an IR temp reading shows a cooler than normal hot end. This would tell me someones curve changed. Replacing a thermistor is a cheap test and may be the proper fix here.

Hah, that's funny, I ordered a Makerbot thermocouple a day before I started this the thread! Still waiting for it to get here XD. Basically, the wires broke about 3/4 of an inch from the hex head of the thermocouple, and so I tried crimping, soldering, and heat shrinking it as best as I could. I can get a reading off of it via multimeter on ohms, but it might not be right. Anyway, will replace that when it gets in. I also tried a print at 200C, and it worked flawlessly, so I think I found my issue. Will try more prints today.

Edited 2 time(s). Last edit at 06/22/2015 10:01AM by MegaRocketPenguin.

Ok, so I took the temp down to 180... And it did it again. Went to 185, and did it again.
[imgur.com]
The first layers usually always come out great. But by the time it gets to the 10-15-20 layer, it begins failing, and a few layers later, it isn't extruding. I have to manually pull out the filament, and put it back in for it to extrude again.
Should also mention that I am using a slightly bigger nozzle (mass wise, the hole is still.4) and is also a bit longer than the original.
Can also confirm 215 is too hot for it as well. Will begin testing temps every 5 degrees to see if I can find something.

And now it does this, at 190C
[imgur.com]
Why?? And what is the solution?

I'm thinking about replacing the drive cog/gear. Sound good? What do you guys recommend?

K, so I am printing a test at 190C... And I find out, that when you can notice the print beginning to fail, if I pause the print, immediately unload and reload the filament with the scripts on the machine, it begins printing perfectly again for another 10-15 layers...
Why??!!!!

[imgur.com]
How do I solve this a issue?
Horizontal fills come out very airy/completely failed.