Unfortunately not removable. I can’t see or access it even with a tiny mirror on an extension, just smell the strong waft coming from the wall cavity through the hole under the wall heater. It’s too tight a space to see into.

I’ve reversed the air flow to blow the smell back into the wall a bit and have scrunched up some puppy pads to somewhat stuff the exit with, hopefully containing some of the smell.

A tissue dabbed with nilodor has been stuffed into a paper cup and a paper towel tied over the top so it can evaporate out but the cat can’t touch or lick the oil.

Ants outside the foundation are carrying away tiny pieces of something so while it will suck in the heat hopefully scavengers are right on it 🤞