Issues with filament breaking inside the underside tubing of your AMS?
This is a common issue and is not necessarily due to moisture or UV.
Sometimes this is just due to the stress on the filament either inside the tube since it is no longer wound on the spool, or by the gears clamping on the filament.
Even though opening the AMS is quite easy, I prefer not to have to remove the spools, desiccant containers etc as this takes more time.
I decided to quickly design an access panel that could be used underneath the AMS.

This allowed access to the PTFE tubes and from there I can use filament to push broken bits out to the front or back (also allows pressing the button (with a tool) that allows the filament through the back, sorry don't know what to call it).

N.B. Please ensure your desiccant containers do not open if you turn the AMS upside down to access the panel.

I designed the panel in 3 parts:
Surround to be secured to the AMS with double sided tape
Panel to seal the hole (uses foam to ensure the hole is sealed).
Slide in door to add pressure to the panel and keep it sealed.
Depending on the tape and foam you use you may need to vary the thickness of the panel when printing or add some tape to the top to increase the pressure provided by the slide in door.

Warning: Cutting a hole will probably invalidate your warranty.

Tape and Foam I used:

https://www.amazon.co.uk/gp/product/B01LQILBYS

https://www.amazon.co.uk/gp/product/B0BXKVDW63