the the printer port on the computer an add in PCI card or built into the mother board?
If its onboard, you need to check in the bios that it is in EPP or ECP mode.
If it is a add in card, then the recourse address is going to be different then the address in Mach3.
You need to check in device manager what the recourse values are (normally 4 different hexadecimals)
You will need to put each one into the mach3 address field for port 1 and see which set of addresses runs the machine the best.
Also, if its a xylotex controller based off of what he was putting out years ago, you will have to deal with the resonance issues that I delt with until going to a G450 drive.