No problem.
A motion controller is an electronics board with an FPGA or microcontroller which communicates with the computer side software (e.g. UCCNC) and then the microcontroller produces the signals to make the motions and other things and sends those signals out.
A breakout board is a board for interfacing, usually to isolate and level shift signals.
This is nessessary, because for example you can't drive a power relay from a weak TTL signal of a motion controller.
Also industrial sensors usually work with higher Voltage, mostly 10-30Volts and you can't directly interface those to the motion controller which accepts TTL (0/5V) signals only.
The other reason to use a breakout board, because noise then can't get back to the motion controller, because the breakout board optically isolate the signals which means the signals go through optocouplers which transfers the signal in the form of light without electrical connection between the input and the output of the optocoupler.
These cheap Chinese machine with USB connection usually have a combined USB motion controller and breakout board integrated on a single board.
This means that if you buying one of them and want to replace the board then you will need a new motion controller and new breakout board and so you will have to rewire everything which requires electrical knowledge, because your new breakout board will very likely have a totally different pinout and even totally different functionalities.
The 6040 machine wiht LPT port connection does not have a motion controller at all, it only has a breakout board with a LPT port connection (DSUB25).
So, you can connect that to one of our motion controllers and then configure the UCCNC to the pinout of the breakout board in your machine.
BTW, we have posted a thread in which we have attached the settings file for these 6040 machines.
And yes, the same machine is available on e-bay with LPT port connections. You can even see on the e-bay listing photos if it has USB or DSUB, so just view a few listings and check the photos and look for the DSUB25 connector...