Oh sorry misunderstood and also I have forgotten about the parallel port in which are inputs and which are outputs as it has been so long since I have used it. Pin 16 is actually an output so you cant use it, you need to use 10 to 13 or 15, so if you already use them then the only option is to get a second PP and use that. There may be other options depending on the way your limit switches are wired, if they are normally closed switches then you could wire them all in series and only have to use one input, that would possibly free up some inputs for you.
Hood