Solved Underextrusion?

Hi, everyone. I'm new to the forum, having just gotten my hands on a third-hand Robo3D for a song. I'm a total greenhorn to 3D printing, so I realize it's going to be an uphill battle with what I gather from the previous owner is a questionable unit. It came as confusing jumble of parts, most of which I didn't even know the names of.
Anyway, I've figured out enough to try a couple prints. The problem is that the extrusion is so thin it curls and the layers barely hold together. My prints look like shredded wheat. I am wondering if it might be a case of a partial blockage.
I've tried heating, pushing filament in, partially cooling, then pulling out to try to remove an obstruction. I've also unscrewed the nozzle, burned out the plastic with a torch, then soaked it in acetone. It still seems to be extruding less than it ought to.
I would post a picture, but my account is so new that I have to post three times before I'm trusted enough not to be a spammer! Does anyone have advice? Am I going to have to disassemble to pull out the hot end? Thanks...

 

Not sure about the firmware, but yes, the fan does run. I know the nozzle is clear, and I can push filament through. I guess what comes out is thinner than the hole, but not by much. It does curls strangely, and can dwindle to a spiderweb at times. Is there a good video somewhere to show me how to clear the hot end?

 

Now that I study it, I'm not so sure about blockage. It does curl a little, but I can extrude a width that's easily as thick as the nozzle.

What I see when I watch it come out if fluid extrusion, then it seems to freeze and stall. Then more comes out, maybe crooked for a while, but it evens out. And this is with the extruder hanging in midair, so I'm guessing the plastic is cooling just by virtue of not being in close quarters to the bed and the warm, newly extruded mass.

I took a video, but I can't post any links yet. I'll need to post another couple times, and then I can link to that, plus a picture.

 

Oh - another potential problem is that the bar for my x axis isn't parallel to the bed. It looks like the sides aren't at even heights on the lead screws. I guess I can somehow unplug the wires from the pieces that travel up and down, get them even, and then plug them back in? Would having the x axis at an angle cause my callibration box to look like a "shredded mini wheat?"

By the way, I greatly appreciate all of the help...

 

Thank you. I easily fixed the uneven x axis, and the videos were a help. I think the "underextrusion" problem I thought I had boiled down to bad PLA. I upped the extrusion multiplier a tiny bit and set the layers to print thinner, and I was getting better results, but then my new spool of PLA arrived, and I can tell it extrudes way more evenly. Anyway, this seems to be fixed. Unfortunately, I can't get through a whole print with the new PLA yet, because now I have a "temp fall error" that pops up after about three layers every tim

 

Yes - that's what I was just reading about when your reply popped up. I'll give it a try. Maybe I'll just order some thermistors so they can be on their way. Can't hurt to have a few lying around. I gather they like to go out at inopportune moments. Just a little daunted to try and replace one, but I'll man up and give it a go. This was a $200 third-hand printer, and I got into it knowing it would force me to get in under the hood rather than just unbox and print. I figured that would really plunge me into 3d printing. So here I go. Thank goodness for the forum.

 

Well, well, well... Turning the fan off did the trick, and the temperature held through the whole print. The new PLA, however, doesn't extrude as evenly as I'd hoped. It seems to stop for brief periods, then lump up and smear. Hopefully I can attach a picture...

If you'd seen my first attempt seven tries ago, you'd know how far I've come. But it's still got that "shredded mini wheat" look, plus these new boogers on the side. What am I doing wrong?

 

I tried a little oil, but with the same result. Here are some pictures. I'm not sure what parts of the printhead are original and what are mods. Now my problem is that the print head is tearing my tape off as it puts down the first layer, although as it ploughs through, it must

 

False alarm about the nozzle ripping the tape off... I figured out that the set screw was loose on one of the lead screws, aso only one side was doing the work of lifting everything.

 

The blue tape is because there is a chip in the bed, and it gives me an even surface. I could probably do without t, since it's a pretty small chip, and unlikely to often be under a print - at least not the small test cubes I've been doing. The heat bed does work, yes.

And yes, I am still having extrusion issues. I had liked the looks of the white filament coming through the nozzle when I extruded it manually, just to watch, but in an actual print, layers have a hard time sticking to one another. There are also gaps, an then the nozzle will drag across and smear the uneven layers it laid down on the previous pass. I also have been leaving the fan off. When it kicks on, I inevitably get a "temp fall" error.

I don't know if this will work, but here's a link to a video of the first few layers of a hollow 20mm cube...

https://dl.dropboxusercontent.com/u/22079358/2016-07-01 19.43.16.mp4

Thanks for all of your help! It's been encouraging to have everyone chiming in. I'm pretty new to all of this.