Hello Everyone,
So I recently pruchased my first 3D printer, a Printrbot Simple Metal from Craigslist, and I am addicted to the hobby now. It is a Simple Metal without a heated bed and a Rev. 4 board. Initially, the seller said it had issues with z-axis calibration and he didn't have time to troubleshoot, so I thought I would give it a try. I did get it to work properly quite quickly by downloading the default Start G code from github, and it prints like a charm. The print quality is good, the settings all work so far. Now onto the issues.

1. So, since day 1, I noticed that when I try to home the printer, it successfully homes, but it sounds AWFUL while doing so. It seems to me like the motors are trying to force their ways past the x/y limits and then it gives up and sets a "home". It does this every time I home, but not when I make the printer move to its extremes manually within pronterface/cura/repetier. I have noticed from YouTube videos that this is not the norm by any means. I have attached a video you can watch to see for yourselves. There also seems to be a subtle cracking noise when homing the Z axis as well which I have been unable to find a cause or remedy for.

2. The other Issue is the fan will not work. I know it is receiving power because I have tested it with a volt meter and the connection has an output of 12v. Also, the fan gets EXTREMELY hot when I send the M106 command, but the blades will not turn. I tried replacing the fan and testing both old and new with my own 12v power source and they both work great. Just not when connected to the printer. I made sure the printer is connected correctly and the wires are all good. Someone mentioned a "MOFSET". I am a beginner when it comes to electronics and I have been having a lot of trouble finding out how that can be an issue/be fixed. I am using a desktop fan now and that works perfect for printing, but I would still like to get a more direct and controlled output as far as cooling goes.

The most important Issue at this time for me is the motor issue, I want my printer to last and so far the prints come out great so I believe it is worth a try to fix. Thanks in advance for any replies. Here is a link to the video: