Bosch Glue Pen Replacement Washer

Bosch Glue Pens have a tool-breaking weakness, it's the rubber washer near the tip which shrinks over time and won't let glue sticks through.

The rubber washer is supposed to let the glue stick through when pressing the feed trigger, while keeping it from coming back out when the trigger is released. Over time, the rubber washer shrinks, and pressing the trigger just deforms the washer and the stick doesn't advance.

This simple washer replacement should be adequate until it shrinks too, in a couple of years of proximity with the hotend.

I used a low infill with Bambu's TPU for AMS, which is pretty inflexible.

You'll find good tear down instructions at:

https://www.electrobob.com/bosch-glue-pen-teardown/

I recommend slicing the annoying label along the plastic shell seam to avoid it coming unstuck.