How do I make this remove limbs multiple times?

I'm trying to make it so when a person sits on a seat and a button is pressed, a part comes from the ceiling (invisible) and removes limbs, it works a few times but then it just stops working.

local debounce = false

function onTouched(hit)
	if debounce == false then
		debounce = true
	local human = hit.Parent:FindFirstChild("Humanoid")
	local arm1 = hit.Parent:FindFirstChild("RightHand") 
	local arm2 = hit.Parent:FindFirstChild("RightLowerArm") 
	local head = hit.Parent:FindFirstChild("Head")
	local scream = Instance.new("Sound")
	scream.SoundId = "rbxassetid://147758618"
	scream.Volume = 2
	scream.MaxDistance = 250
	scream.EmitterSize = 10
	scream.PlayOnRemove = false
	if (human ~= nil) then 
		scream.Parent = head
		scream:Play()
		human.Health = 80
		arm2:Destroy()
		arm1:Destroy()
		wait(15)
		debounce = false
		end
	end
end

if (script.Parent ~= nil) and (script.Parent.className == "Part") then 
	connection = script.Parent.Touched:connect(onTouched)
end

Also, if there's a way to execute the script on the player whos sitting, then that would be easier. I don't understand how to find the player who is in the seat, and I know it's a better way to do it. So if you could help me either way then thanks.