This receiver came to the shop with Standby/Mute malfunctioning. If your mute function fails, the receiver will feedback when you transmit. This could result in a very expensive repair to your receiver if not addressed quickly. I have seen this fault a few times in the past, so thought it would be great to share this with you. Normally the standby function of the NC-300 is very desirable, no annoying pops when cycled. I have actually put Nationals circuit in other brands of vintage receivers. The fix I am demonstrating in the video, is quick & inexpensive. However, it would be best to replace the main filter capacitor, since it is obviously nearing the end of its life. That is not the option that the owner chose. So take it for what its worth. The video will aid you with discovering the fault. However you wish to proceed after that is your decision.