I’ve been very pleased with the performance of my LGX-Lite extruder – until I encountered this problem:

LGX-Lite drive gear

The arrow points to 2 teeth that have become mis-shapen. When these 2 teeth reach the gear wheels that extrude filament all extrusion stops. But the printer (of course) knows nothing about this so it keeps moving the hotend as usual. The net result is a ruined print.
The good news is Bondtech sells a replacement gear for $5.00. Here is the link for ordering the gear:

https://www.bondtech.se/product/lgx-primary-gear/

If this problem happens to you note that it is possible – if you are VERY CAREFUL – to remove the gear from the extruder and replace it without disassembling your hotend. Here’s how to do this:

1. Loosen the 2 screws on the front face of the extruder
2. Remove the motor from the back side of the extruder. The motor wires will give you only a small amount of movement to allow pushing the motor off to the side.
3. Remove the back plate from the extruder housing. Note which is the top of the back plate so you can put it back in the proper orientation.
4. Very carefully pull the drive gear out of the extruder housing. With the back plate off the entire contents of the extruder can fall out. If this happens you’ll have to take the whole thing apart in order to reassemble everything. When you remove the drive gear the shaft on which the gear turns may come out too. But it is easy to replace it if this happens.
5. Reassembling is easy – just put the new gear on the shaft, replace the cover, re-attach the motor, and tighten the 2 screws on the front of the extruder.

Shortly after I installed the new gear I got a piece of filament jammed inside the extruder. This happened because I tried to change filament colors before the hotend was fully up to temperature, so a small piece of partially melted filament got stuck in the gears. To fix this I removed the front cover of the extruder , then removed a couple of pieces that were in front of the gears, and then carefully removed the piece of stuck . Here is what the inside of the extruder looks like (without the stuck filament.)

23 Jan 2023