MK8 extruder stepper motor clicking and not giving a uniform extrusion.

Hi guys, I have bought a reprap just recently and set it up. All is going well so far except for my stepper motor in my extruder is clicking and shaking. When I test it on pronterface it starts well but when it approaches the last bit of extrusion it starts clicking (moving and stopping continuously) and eventually stops. Like it's getting clogged in something. I have checked the mechanism and nothing is blocking it. I have switched plugs with the x-axis and it turns smooth. I have tried reducing the current from the stepper driver but no effect. I have increased the steps per unit in the marlin. The higher the value the smoother it gets but it looses its calibration. I have reduced the maximum feedrate and maximum acceleration but still not much improvement. I wasn't able to print until now as it keeps on freaking out while printing too.

Has anyone of you ever encountered this kind of problem? I'm a newbie in 3d printing :/

Any help is much appreciated!
Thanks

Manuel

It's yours the one with the plastic black box or the one with an aluminum lever and spring tensioner?

It's the one with the aluminum lever and spring tensioner.

Check the plug on the board. Make sure there aren't any loose strands of wire touching other wires.
Your tensioner may also be too tight.

Controlling from Pronterface: Are you pressing the extrude button multiple times? This sends too many commands and your controller has to slow itself down to keep up.

Your heater block may also not be keeping up with your extrusion speed. Try slowing your extrusion and watch your temperature to make sure it's not dropping too low.

I have checked all that you mentioned and no improvement so far. I am suspecting it's a firmware setting as I have checked anything in electronics and mechanical parts which may interfere and found nothing so far :/

OK guys, I think I've solved the problem. Turns out that maximum E velocity must not exceed 999. It was 1000 and reduced it to 950. Worked well until now

It's the barrel plain stainless steel or does it have a PTFE liner?