PCI-E Parallel Card Problem

It is also possible that the config which says "port in use" or similar is the right one, and that lp or some other module has grabbed the port.

Try that config, then see is lsmod shows something like "lp" or "parport_pc" which might have taken over the port.

I am on the phone so I can not point the exact location, but there is a paraport half tester that comes with all later versions of linuxcnc for both usual addresses, x387 and x287.
When you start linuxcnc from the menu you are presented with a config picker, under "apps" there are both testers, chose one, when asked if it should copy it to your home folder answer yes, after opening close it.
Now open a file explorer ( Linux mint-caja, wheezy-thunar, ubuntu-nautilus, etc), in your home folder you will have a linuxcnc folder, then configs, then something with 387 or 287 (depending on what you chose at the picker), open the .hal file with a text editor (mint-pluma, wheezy-mousepad or leafpad ???, ubumtu-gedit), find the line with address of parport, replace that address with the one you got from "sudo lspci -v", save and close.
Right click on the .INI file in that same folder, choose " open with" and enter "linuxcnc" under "enter custom command".
If all is good, a window with 12 buttons and 17 LEDs opens, 12 outputs and 5 inputs.
Now find a short piece of wire ( or a thin hair pin) and locate the pins with numbers 10,11,12,13,15, short one of them with the connector ground, the corresponding input LED should change to green.
If it does turn to green, connect the machine and start using it, if it doesn't go back and change the address, save, restart the computer and test again.

PS, I hate auto correct, it says "half tester" instead of "hal tester" as it should.