Extrusion stopping mid-print

[lennox81]

Been lurking on these forums for a while now and the time has come to make an account and post. So I've been running my machine since August (fully assembled, V3b hotted, have printed nothing but PLA) and love it, don't run it every day but its had a fair amount of use and I have not really had any major issues with it at all. Then about two months ago I noticed that the fan blowing on the extruder motor would make a weird noise (but seemed to be blowing normally) but usually if I let it run for a minute or so or turned the machine on and off a few times it would stop making the noise and behave normally. Not sure if its related but thought I'd bring it up. Now this next issue started about a month ago (and at a not so great time because I needed parts for a senior design project) and has happened fairly consistently since then, in fact my memory int perfect but I can't remember if I have had a totally successful print since except maybe really small things that are quick prints. Anyway I will be printing something and its not always consistent when it happens but usually an hour or so into a print plastic just stops coming out of the nozzle. If i notice it quick enough I can push the filament in a bit more an it starts extruding normally again but with the few missing layers it is printing in mid-air and obviously that doesn't work out so well.

I have checked that the filament drive tension screw is set properly (and since i've only used matchbox PLA and the black filament the printer comes with I don't need to change that almost ever)

Checked to make sure theres no filament jammed up in the extruder gear

Don't think its a nozzle jam, any prints dimensions match up well and calibration squares print great so I have no reason to think this

Obviously the extruder motor isn't stopping since when i push the filament in more it "catches" again and keeps printing.

Can anyone help give inside on to what could be causing this? (P.s. I wouldn't hate an excuse to upgrade to the v4 haha)

[sthone]

The fan noise is normal, on the older models the extruder fan and case fan are both 12 volts wired in series and feed 24 volts from the board that noise is just when they are balancing out (or something along those lines) let them run for a bit and it will stop we've all heard that noise at one time or another it's nothing to worry about.

The extrusion stopping could just be the signs of a partial clog. Even though it feeds most of the time some burnt PLA could be in the nozzle and occasionally burn free and clog the tip a bit. It might be time to run some cleaning filament through your hotend and maybe do a few cold pulls. I have this happen sometimes with ABS too. If you look close enough when it's extruding (off the build surface say during the prime) you can actually see the filament is thinner than the normal extrude should be. Most of the time I just use the small allen wrench too push everything out of the hotend from the top and then run some cleaning filament.