Many of these amps have been coming thru the doors of my shop. Every one needs new filter caps. After 60 years of service, there is no need to test or hope they will get by for a few more years. Just change them. Use the highest quality possible, examples would be CE manufacturing or F&T. Dont cheap out or you will pay the price. These amp have served us all well. They deserve the best to ensure more decades of quality tube audio! If you do not feel comfortable performing this task, D-Lab is here for you! I promise professional results at reasonable cost. My shop is focusing on Dynaco/Marantz/Fender/Gibson/Johnson/National. Contact me with your needs. Reputation is everything.