I have a lot of couches in my house and for Pesach, I obviously take off all the cushions to clean out what is under there but I want to know if I have to also reach my hand further under, into the places you can not see, to try to pull out any crumbs or is that unnecessary? I attached a picture which gives a visual of what I am referring to.
You must clean out as much as you can reach with your hand. Best is to pour a cleaning agent which will make all the crumbs of food inedible.
שוע”ר תלג, יט-כ.