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)