Extruder Motor Replacement?

[Vivid8]

New to the boards and I've got a problem, searched the forum and have found similar problems but all solutions people found haven't work for me. I've had the FFCP for a few months now at work, it runs 8+ hours a day 5 days a week. We switch back and forth between left and right extruders to rest the motors and gears. Well we've been trying to use the right, but the feed is no longer consistent. It just stops randomly during printing, no clicking, no anything. It keeps moving along like it's printing but no filament gets extruded. I've switch colors to check if it's the filament being used, it isn't. I've disassembled the extruder in question twice and fully cleaned it. The first time the teeth of the feed gear were pretty filled with filament and had high hopes it was the problem, no dice, the second time it had some filament in it again but not as much. I've switch the left and right extruder cables and have certified the right physical extruder is where the problem is because the issue does NOT persist when the right cable is connected to the left extruder but the issue does persist with the left cable plugged into the right extruder. I'm thinking the motor is failing because while the problem is consistent the frequency of it seems almost random. I've pulled back the guide tubes and run the line by hand to feel the tension, at random intervals the extruder simply stops pulling. At first I thought it could be worn down teeth on the feed gear, but after checking they are in top shape and very clean (now). It seems to me the gear simply stops turning to feed the fliament intermittently. Also, when it stops how long it stops for is seemingly random. When I do "Load Filament" it can stop for a fraction of a second to a few seconds before it typically starts feeding again, however when printing once it stops feeding it never starts again. To clarify I've taken apart the extruder and cleaned the feed gear, also the extruder tip, the inner pipe, everything. Put the tip through a acetone bath and cleared it of debris and then sanded the outside free of build up and such. So I'm virtually positive there is no blockage or such gumming up the mechanism. An interesting note, when the feed does stop and it quits pulling the filament if I push the filament in it immediately will begin feeding again and sometimes I have to push rather hard as though there were a blockage, but as I've said I have continuously taken apart and cleaned this thing. It will continue working after that until it randomly stops again, every time it quit if I push the filament in it will always start right back up. It will just fail randomly again.
All of this together leads me to believe something is physically failing with the extrusion unit, since switching the cables doesn't move or end the problem. So what I'm asking really is from experience or sheer knowledge does anyone have a pretty good idea of which part specifically is failing on me? The gear looks good, so I don't think it's the condition of the gear, if the gear is failing to turn I'm thinking that's the motor failing and not the stepper motor driver or the extruder circuit board. If someone could provide an answer that'd be ideal, otherwise if someone could provide the steps or a link to the steps or video (prefer video) on how to trouble shoot this to determine if it's the board, driver or motor I would be thrilled!

[jfkansas]

Generally it is the cable that goes bad. The steppers are pretty tough and I doubt both would go out at the same time. You can switch the steppers from left to right, just have to put the opposite side plastic on.

It is possible a stepper driver might be going out on the board. I would drop in a new stepper and cables before switching out the stepper driver.

[Bassna]

I had this happen with this crappy filament I was using. Just mid print, would stop printing, no clicking, but would still be going. Switched back to my Hatchbox filament and have not had the problem since. Probably not your issue, but maybe try switching filaments?

[curious aardvark]

he's tried switching cables and filament.

Sound's like the motor to me.
Last time I looked a stepper motor was only about £13.
Might as well get one and try it. if it's not that, then at least you've got a spare :-)

[Nargg]

http://www.flashforge-usa.com/shop/p...ruder-set.html Replacement extruder head setup....

[Vivid8]

So I've replaced the motor and the problem has not stopped. I decided finally to remove the fan and run "Load Filament" and see what exactly was happening. Strangely the feed gear never stops spinning, it never slows or sputters. In fact, nothing goes wrong. It magically stops feeding. I've checked it multiple times now, the machine continues to run but the filament stops feeding through. I simply have no idea what to do now.

[ffvader]

did you ever figure this out. I have almost the same problem with my left unit.
although mine doesn't seem random, it seems to happen at the same time.
I run a "load filament" and put in the filament, it starts to extrude and then slows and finally stops.. it will start up again if i push down on it, but then after 30 seconds-minute it will slow again and finally stop.
i have taken apart the unit and cleaned the gears (this unit is only a few weeks old and has probably less than 20 hours on it)
i saw a video on a maker bot, where someone fixed that type of issue by tightening up the plunger? but since our's is a different setup, i didn't know what i could try to adjust/tighten.
anyone have any thoughts?

[lithgowlights]

When I had a similar issue on the Dreamer it tuned out to be the small tube between the extruder head and the filament drive motor. This small Teflon tube looked ok, but must have had a buildup inside as as it heated up it simply became sticky or swollen and did not allow filament to flow evenly. Depending on the filament I was using I would not hear the gear slipping, so it was as if the filament was simply not extruding.

i cleaned the tube, put it back in and no difference was seen, but eventually I replaced it with a spare I had and the printer ran like new. Not sure if the FFCP has the same tube, but I think the head unit is very similar so it may be something to look at