How to detect the position of a part?

I am making a sliding door thingy. Everything works, but I only want it to open if its in a certain place. The problem is when I click it nothing happens.

Any ideas?

local model = game.Workspace.BorderDoor

script.Parent.MouseClick:Connect(function(playerclicked)
    if model.MainPart.Position == Vector3.new(75.52, 14.85, 660.725) then   
        local pr = playerclicked:GetRankInGroup(4831829)
        if pr >= 10 then
            for i = 0,0.139,0.001 do
                model:SetPrimaryPartCFrame(model:GetPrimaryPartCFrame() * CFrame.new(0,0,-i))
                wait()
            end
        end
    end
end)