Just bought a used Solidoodle 2, need help troubleshooting issues (Page 2 of 2)

I switched the X and Y plugs and the Y motor moves great, X motor does not move at all, I think it is the driver. Is it possible to easily upgrade the motherboard, without having to do much soldering? I don't have those tools, but I could find someone to borrow it from if I need to. But I'm willing to spend a little bit of money if it means getting a more up to date motherboard.

It's likely the stepper driver.  Those are the green PCBs in the picture below, and they can be unplugged (unplug USB and DC power before doing any unplugging to protect microcontroller).  Earlier I suggested sapping Y with Z because those are the same size motors, and I thought their stepper driver potentiometers (they are on there, but they are very small) might be set more similarly.  X motor is smaller, probably NEMA 14.
http://reprap.org/wiki/File:Sanguinololu.jpg

Anway, you could plug your motors back in the way they were, and try swapping Y and Z steppers, as that would again narrow it down to board or stepper.  Perhaps wait until a more experienced member confirms that this is wise, since those steppers could have different potentiometer settings.

These are the steppers: http://reprap.org/wiki/Pololu_stepper_driver_board

I didn't know you could just unplug the stepper drivers, that makes it much easier to replace then. It's pretty cheap, so I'm going to try that before anything else. Is there a simple, easy to understand walkthrough for how I would do that? If I'm just replacing one stepper driver, should I just reinstall the firmware? (I don't know how to do that, because I didn't build this thing)

Safest way to do it is to swap them out with the power off. On the back of the drivers, you will see a few notes like "Ground/GND". Make sure the ground pin matches the orientation on the board itself...some stepper drivers need to be flipped 180deg, some not. And no, you don't have to flash the firmware for this change. But if you swap for a DRV8825, you need to adjust the EEPROM settings for that motor.
Fastest way to get a new stepper driver is at Fry's or Microcenter if you have either close to you.

Hey guys, update!

The new stepper drivers came in the mail today (got five of them, you know, just because.) Swapped a new one in for the old Y driver and it works great! Been tuning it, I think I have it where it needs to be, I plan on messing with it a little more just to make sure it's good. Everything else appears to working great. No more flickering lights. We'll see how the first print goes.

Thanks so much for your help, everyone!

Hello, I'm back with more problems!

Printer is doing better than it used to, but something's definitely not right. Been trying to diagnose the problem with just information I can find online, but it's difficult for me to just choose a route and get to work.

Biggest problem right now is still the Y motor I think. Circles are misshapen, normally "squashed" along the Y axis. It runs smooth, except sometimes it just "skips" and starts printing in the wrong place, ruins the whole print. This is not very often, but it seems to happen to like 2 out of 3 prints. I've been trying to tune the potentiometer more and I think I'm getting closer but it just takes a lot of time and patience to do that because if it makes just one skip then I have to start all over again.

These belts and carriages though, absolutely suck. First of all the 1.5mm hex screws are stripped so I can't do anything with that, I just want to replace all the rods. The belt is attached to the Y carriage by some horrifying bolt and washer mess, I'll attach a picture soon.

I would replace the carriages, and rods, and I think that's what I want to do next, but I can't print anything accurately enough. Is someone willing to print those parts for me, and I can reimburse them? Or is there a place where I can just order these?