How to Check glue level

Back in May, I neglected to replace the glue cartridge when replacing the rest of the material kit and ruined a model because the SD300 ran out of glue during the next build. Since then I've tried to always replace the glue cartridge in sync with the PVC roll.

I learned to double-check the glue cartridge's capacity by shining a high-intensity LED flashlight through the side walls, which reveals the glue level as a bright line on the wall.

Today I was startled to discover the glue cartridge was essentially empty, even though there was plenty of PVC left in the material kit. There should've been plenty of glue left. Notice the bright line is all the way at the bottom.


I still had the glue cartridges from two recently-exhausted material kits. There was a little glue left in one of them, but that's how much is usually left over after a kit has been used up. The bright line is near the bottom.


When I checked the other "empty" cartridge the LED light showed it had a lot of glue left in it. Notice how the bright area is well above the bottom!


Probably I got an 'empty' cartridge swapped with a non-empty one when changing between colors recently. I shouldn't leave the empties nearby. It's fortunate I discovered it before the machine completely ran out of glue.