Are you using OEM cartridges or a 3rd party bulk system? How old is the machine and how long has it been since you replaced the dampers and maintenance station or cap top? Are you letting the machine sleep and auto clean?
In general, if you aren't using the machine everyday, you should be running at least a nozzle check. Also, if the auto cleanings aren't turned on, leaving the machine without running for a few days will always end in missing nozzles. Poor daily/weekly maintenance and failure to replace maintenance parts when they are recommended are usually the culprit in these mystery nozzle drop out issues. That and the age of the machine but these 1624 aren't old enough for that yet.