Not Extruding /missing printing issue then please check following.
It is for most DIY 3D Printers but exclusively PRUSA i3
try to deal one Solution at a time and see if problem solved
... Check and tighten and align filament feeding gear often its elan key screws get loose and will move
... Check alignment of U-groove wheel bearing with filament passing holes if it is in center if not chenge washer with more thinner one.
... Adjust on logic board Potentiometer (variable Resistor) that will adjust the voltage of motor
A. multimeter plugged in serial to one motor wire - also described on that wiki - can help : turn down the pot until the motor won't have enough current to move then back up a little to give 1.25 to 1.5 times the current you measured.
Also the sound helps - motors cry high or low when current is not appropriate.
B. Measure the voltage on the wiper of the pot ( trimpots) you are adjusting and set it to 0.4V. That will give 1A.
If drivers give out 0.4 to 0.5 A per phase then everything will works fine.
The temperature stays quite low on the motors, never above 50°c ( Ideal is 40°C or less).
Also another idea if you can use strong rubber ring and a separate mounting plate, so that should insulate the hot motors from the plastic and keep it from melting. It also quiets the motors and reduces vibrations.
Most of the times As long as they don't melt the brackets it is not a problem running motors hot.
The resistance increases when they got hot so the performance drops with constant voltage drive
They are rated for about 100C. I.e. the current rating is for 80C rise. Please run them well below that to prevent the brackets melting.
How to deal with variable:
Setting up stepper motor's voltage and current.
Too little current and your stepper motor will skip steps, too much and it will heat up and warp the plastic motor mounts.
The X axis, the Y axis and the Extruder are the only motors which are always activated, and so they are the only ones you can adjust by temperature.
The Z axis only activates when it is being used,
after running 20 minutes check the temperature of the motors to be sure if adjustment is correct it wont heat up. It is good if running at 50 degrees celsius or less. But Ideal is 40C degrees or less feels like a warmish/hot shower.
To turn it down, adjust the trimpot counter clockwise. To turn it up, adjust it clockwise. The trimpot is extremely sensitive, so very small adjustments may make a big difference. we advise adjust about 1/8th of a turn at a time to start with, then fine tune it with even smaller adjustments.
1 Ampere current is about right for the standard high torque NEMA 17 we use. They are rated at 1.65A, two coils on, 80C rise. With the current is set to 1A, when both coils are on the driver gives 0.7A each. The temperature rise in the motor will be 80C * (0.7/1.65)^2 = 14C, so the motors only get warm in ambient conditions.
The torque will be only 0.44 * 0.7/1.65 = 0.19 N.m.
Stepper motors run at their maximum spec will get to 100C, which is way too hot for plastic brackets, so we use high torque motors and under run them. The particular motor we use also has the correct voltage / current ratio to hit the sweet spot of the Pololu / driver / Motor Controller.
If you reduce the current until the motor does not get too hot to melt the plastic brackets. And after if you don't have enough torque to move the axes then means the motor is not suitable or bad.
Also above setup require if any of the motor is getting extra hot.