Works, but pretty buggy, anyone can figure out why?

The tool works, everything from clicking buttons and pressing down keys, as expected. But, if a player were to spam equip and unequip the said tool, clicking buttons would double the expected value. Say if I equip and unequip and then equip this tool back, and I click on Plus button, the value wouldn't go up by 0.1, but rather 0.2 or straight to the maximum. Any ideas why?

I've tried putting the mouse1buttonclick on the bottom of the script and only run the function if the tool is equipped, but it decided not to run at all.

For example, if I put a ToolSelect = false, and ToolSelect becomes true when the tool is equipped, and false when tool is unequipped. And then I put the condition to run the function when buttons are clicked is ToolSelect == true, but... nothing. Not working at all.

My main question is, how to disconnect the mousebutton1click when the tool is unequipped or make it not doubling the values?

local InfoGui = game.Players.LocalPlayer.PlayerGui.InfoGui.Frame
local passId = 361436914
local player = game.Players.LocalPlayer
local PlayerVIP = 0
local mode = nil
local Targ = nil

if (player.UserId >= 1) then
	isVIP = game:GetService("MarketplaceService"):PlayerOwnsAsset(player, passId)
	if (isVIP) then
		PlayerVIP = 1
	end
end

repeat wait() until player.Character

local value = 0

function onMinusClicked()
	if( mode ~= nil) then	
		if mode == "Transparency" then
			if(value == 0.5) then
				InfoGui.Frame.MidLast.Text = "Press Q or E to change the transparency value"
			end
			value = math.max(value - 0.1, 0)
			if(Targ ~= nil) then
				Targ.Transparency = value
			end	
			InfoGui.Frame.First.Text = "Transparency: "..value
		end
	end
end

function onPlusClicked()
	if(mode ~= nil) then
		if mode == "Transparency" then
			if (PlayerVIP == 1) then
				value = math.min(value + 0.1, 1)
			else
				value = math.min(value + 0.1, 0.5)
				if (value == 0.5) then
					InfoGui.Frame.MidLast.Text = "Only VIPs are allowed to set more than half of the transparency value!"
				end
			end		
			InfoGui.Frame.First.Text = "Transparency: "..value
			if(Targ ~= nil) then
				Targ.Transparency = value
			end	
		end
	end
end

function onKeyDown(key)
	if (key~=nil) then
		if (key=="e") then
			if (PlayerVIP == 1) then
				value = math.min(value + 0.1, 1)
			else
				value = math.min(value + 0.1, 0.5)		
				if (value == 0.5) then
					InfoGui.Frame.MidLast.Text = "Only VIPs are allowed to set more than half of the transparency value!"
				end
			end
		end	
		if (key=="q") then
			if(value == 0.5) then
				InfoGui.Frame.MidLast.Text = "Press Q or E to change the transparency value"
			end
			value = math.max(value - 0.1, 0)	
		end
		InfoGui.Frame.First.Text = "Transparency: "..value
		if(Targ ~= nil) then
			Targ.Transparency = value
		end
	end
end

function onMoved(target)
	if target then
		if not target.Locked then
			if(target.Parent.Name == tostring(player.UserId)) then
				selection.Adornee = target
			end
		end
	end
end

function onClicked(target)
	if target then
		if not target.Locked then
			if(target.Parent.Name == tostring(player.UserId)) then
				Targ = target
				selection.Adornee = target
				target.Transparency = value
			else
				selection.Adornee = nil
			end
		else
			selection.Adornee = nil
		end
	else
		selection.Adornee = nil
	end
end

function onSelected(mouse)
	InfoGui.Visible = true
	InfoGui.Frame.Visible = true
	InfoGui.Frame.First.Visible = true
	selection = Instance.new("SelectionBox")
	selection.Parent = player.PlayerGui
	mouse.Button1Down:connect(function() onClicked(mouse.Target) end)
	mouse.Move:connect(function() onMoved(mouse.Target) end)
	mouse.KeyDown:connect(onKeyDown)
	InfoGui.Frame.MidLast.Visible = true
	InfoGui.Frame.MidLast.Text = "Press Q or E to change the transparency value"
	InfoGui.Frame.First.Text = "Transparency: "..value
	InfoGui.Frame.First.Minus.MouseButton1Click:connect(function() mode = "Transparency" onMinusClicked() end)
	InfoGui.Frame.First.Plus.MouseButton1Click:connect(function() mode = "Transparency" onPlusClicked() end)
end

function onDeselected()
	Targ = nil
	value = 0
	InfoGui.Visible = false
	InfoGui.Frame.Visible = false
	InfoGui.Frame.MidLast.Visible = false
	InfoGui.Frame.First.Visible = false
	selection:remove()
	mode = nil
end

script.Parent.Equipped:connect(onSelected)
script.Parent.Unequipped:connect(onDeselected)