OK thanks. So it's likely back where I it's not easy to get at (in this case). Will need to tear the whole thing apart to get at it but glad we have an idea now.
Made a video showing what I've observed so far: https://youtu.be/twCNbZGTeW0
	
		
			
		
		
	
			
			Made a video showing what I've observed so far: https://youtu.be/twCNbZGTeW0