By looking at the NMR settings files, I could see that neither lockin had values recorded. These files are automatically generated by the computer at the start of each NMR measurement, and saved to a file in the Target Expert folder.
Scanning by using the National Instruments Measurement and Automation program confirmed this. Now, a GPIB device not communicating is a very common occurance, and by turning on and off the lock-ins we cleared the first problem. However, we discovered a second problem.
Repeated National Instruments Measurement and Autmation scans showed only one lock-in and that lockin was outputting gibberish. A closer inspection indicated that both lockins were set to the same GPIB address. I corrected this and turned them off and back on to make sure that this is no longer the case. When the lockins come back on now, they go to the correct addresses.
Performed and NMR measurement to confirm, which will be a separate entry.
But, the measurement worked.