So, I got a Printrbot Simple a few months ago, and have been having a lot of fun with it. Just today though, something popped up. All of a sudden, the motors are moving excruciatingly slowly. Like “I can barely perceive any movement” slowly. I’m not sure why this happened, other than before it started I was typing in Gcode for calibration purposes. All I can figure is that I typed a command wrong, but I don’t know my Gcode very well yet and so, even after looking at the RepRap page on it, I can’t figure out where I went wrong, or how I can fix it. Any help would be greatly appreciated!
I had a similar issue in the past. Still not sure what was the reason, but I resolved it with replacing a Printrboard. Not the best solution, I agree.
Does your printer firmware support sorting values in EEPROM? M502: revert to the default “factory settings” might help. Were you typing this gcode somewhere where it might be stored, like in an init script, or just into a terminal prompt?
Yes Printrboard firmware supports M500 M501 and M502:
@David_Aden M500 saves the values, M501 prints them back, and M502 does a factory reset. So I would say if you did not do a M500, do a M501 to get the values and either do a M502 or just press the reset button. Then do a M501 again and compare.
Try entering M220 S100.
Thanks all! M502, M500 worked. M501 showed all was in order, and the beginning of a test print confirmed.
@Ivan_Krasin Thanks for that tip! I’m glad it didn’t come to that, though. I’m on a pretty tight budget.
@Mark_MARKSE_Emery I was typing it into the command line on Repetier Host. I did use M500 to store it though (not sure what I stored…). Thank you!
@Andre_Courchesne1 That worked, thank you!
@John_Davis I didn’t see your comment before I went back to the printer and tried resetting, but thanks! I think I messed up on a command somewhere, maybe I typed something along those lines.
Thanks again!
M220 sends a speed override command of value S%, so M220 S80 while printing will slow your print speed down to 80%. If you ever accidentally send an M220 S1, you’ll get VERY slow motor movements.
Glad to hear you got it back to normal.
Ah, okay. That makes sense. Thanks!
Thanks @John_Davis ! I was looking for this info recently! 
@John_Davis your hired!