Ask the customer to locate their Backup transmitter, and have them connect it to the ventilator. Log in via TeamViewer and ensure it is operating properly. If they cannot locate the Backup, see if they can find the Spare. If not, if there is a transmitter not currently being used, have them use that transmitter but note the new room assignment. Escalate this ticket to note the missing transmitter and use of Backup unit, Spare, or other transmitter.