What cutting software are you using to send files to the D60U? If you are using Winplot you may need to change your port selection in the cutter setup menu to the correct USB port. This is especially important if your new S One D75 is also connected via USB as well. You can use Summa Cutter Control to test the connection the D60U and to determine which USB port it has assigned. Once you know the correct port just make that change in Winplot and you should be good to go from there. If you are using other cutting software that may change the process a bit, but generally speaking you probably just need to assign the correct USB port in your cutting software to fix the communication issue.
Best regards,
Phil Johnson
Airmark Corporation
(800)527-7778, ext. 112(office)
(509)280-6354(cell)
philj@airmark.com