The membrane is probably drying out but best to talk to the experienced since I've not had to deal with drying  membrane but sure sounds like the little duckling is trying hard. 
Has it been able to chip away more shell and is it yawning?
@New duck mommy 2021
	
		
			
		
		
	
				
			Has it been able to chip away more shell and is it yawning?
@New duck mommy 2021
	