woolValid = true
startPosition = 1

local function dropWool()
    for i=startPosition,16 do
        if woolValid and turtle.getItemCount(i) > 1 then
            turtle.select(i)
            turtle.dropDown(1)
            --Uncomment this is your spreaders are overloaded \/
            --os.sleep(1)
        else
            if woolValid then
                startPosition = i
            end
            woolValid = false
        end
    end
end

local function main()
    woolValid = true

    print("Validating Wool")
    for i=1,16 do
        --For some reason white wool's damage is 64, whereas the rest are sequential....
        if (turtle.getItemDetail(i).damage ~= i - 1 or turtle.getItemCount(i) < 2) then

            woolValid = false
            print("Wool invalid at index: "..i)
        end
    end

    if woolValid then
        print("Your wool's valid. Flip the lever to start the drop.")
        while woolValid do
            if rs.getInput("left") then
                dropWool()
            end

            sleep(.1)
        end
    end

    sleep(1)
end

while true do
    main()
end