I had similar issues with mine at about the same point in time. I fixed two separate items that I found related to the problem and never had a failed print since the fix
1.) replace the cooling fan it is in any way damaged. Mine was missing two blades out of the 9 because a piece of filament swung down into it. Those two missing blades was messing up the cooling. Use one with the same number of blades. Also, make sure your fan is facing the right direction. (sticker side IN) Mine, during one of my nozzle clearing fits, got installed backwards and it jams everything up because the cooling doesn’t work. I also put a dab of heat sink grease on the cooling fins between the heater block.
2.) replace the drive gear on the filament feed motor. They’re $14 and over time they wear. Especially if you use specialty filaments with carbon fiber, steel or stone fill. You can inspect it with a magnifying glass and if the center of the ribs is misshapen or has a different appearance in any way, replace it.
I think you’re right on, Andy. They never said what temperature settings they have been using, but depending on the version of Makerbot Desktop, it could be as high as 230. I have 4 Replicator 2s and I rarely run PLA above 210 degrees. I typically run the first layer at 206, then drop the temperature about 2 degrees every two layers until I get to about 198 or 200. Of course you really have to know your material, and I haven’t found a PLA I trust more than Hatchbox. Another thing that can cause similar problems (that people don’t seem to give enough credit to) is when the actual filament diameter doesn’t match what the slicer thinks the diameter is. For example, if the slicer thinks the filament is 1.68 but the actual filament is 1.82, the machine is trying to push more filament through the nozzle to keep up with the desired layer height and width. It usually is fine in the first few minutes, but eventually the nozzle and tube will get too much material in there and you’ll be prone to having one of these jams. This especially can happen when the filament is getting too hot further up the tube… as it gets soft, the extruder gear slips and starts eating into the PLA rather than pushing it through. The part that makes me think it’s setting rather than hardware is that they said they have changed nozzles and still get the problem. Typing that last part made me think… could they have possibly changed the nozzle to a smaller size by accident and not changed the machine settings? That will certainly cause the problems similar to the situation above. I have about 4 different sizes of nozzles in my toolbox and they all have settings they like best. If you keep having problems, put a .5mm nozzle on that bad boy and see how it prints. I have never seen a jam with this size nozzle.
There might be some buildup of dust, grit, or other substance in the extruder, this would prevent propper flow. I also have a Replicator 2 and I have had to replace the nozzle once before. I have owned it for 2 and half years. It could also be the filament…
I’m willing to bet you have a burned out MOSFET on your board. This is a common problem for the Replicator 2s and causes your fan to spin slower, cooling less.
I try to change the diameter settings of the fillament.
By Increasing it to 1.8 it prints perfect now.
Prob not the solution in all cases. but it worked for me !
Switch of retraction and see if it keeps working then. You will have stringing then, but at least you know then that retraction contributes to it, and you can play with that setting.
Also, did you clean the gear that pushes the filament in? I dissassemble that and clean the gears with toothpick if traction starts to fail.
I had the same problem as Andy explained I lowered my warmup temp to 200c and my print temp is 220c or less. Haven’t had any problems since. (also replaced the heating block at the same time as dropping the temp to make sure no extra goop inside would mess with it)