Hey there, sorry to hear about the trouble with your Fike 63-1165. When it comes to troubleshooting these duct detectors, there are a few common issues to consider. Firstly, ensure that the duct detector is properly installed according to the manufacturer’s instructions, including correct placement and orientation within the ductwork. Next, check for any obstructions or debris within the duct that could be affecting airflow and smoke detection. Additionally, make sure that the power supply to the detector is stable and within the specified voltage range. If everything seems to be in order externally, it’s possible that there could be an internal fault with the detector itself, in which case, it may need to be inspected and possibly replaced. If you’re unsure or unable to resolve the issue, it’s always best to consult with a qualified technician or contact Fike’s technical support for further assistance.