I spent entirely way too much time trying to get one of these style extruders on my Ender 3. Maybe I picked a knock off without realizing it, maybe mine was just defective, I'm not entirely sure.
But it was ultimately the cause for my printer underextruding on certain layers. If you need a new extruder, go for something better than these cheap $20 ones and get an actually decent one.
But on the bright side, my printer is finally fixed! It feels nice to be able to get back into the hobby again.
-Upgraded an Ender 2 pro with this one.
WARNING: buy and ender 3 extruder motor if you plan to do so. Thank me later.
I gave an Ender 2 pro as a present for my little brother and sister. The extruder stopped doing it's job, so I bought one of these for 50 CHF (in Switzerland you pay a lot for anything). But what's good is, it works flawlessly. I wonder if I'll have to tighten the grub screw over time, but that honestly doesn't bother me much. Also aligning the gears was a bit fiddly, but if you pass a piece of fulament through the extruder, it aligns the gears automatically and then you can tighten things down. IMO worth it.
Edit: the yellow spring is extreme overkill. That might be one of the causes for the problems. Too much tension isn't good. maybe try installing the stock spring if you're having problems.
I ended up replacing the whole extruder with a micro Swiss one because it was causing me such a headache.
If I ever have to use the old one, I'll give that a shot.
More power to you. Happy printing :).