Got a question from an owner of a vintage Masi frame about repair. Probably one of the very best things you can do to have a frame repaired (Masi or otherwise) is contact Brian Baylis. Brian was one of the artisans at Masi California and is widely regarded as one of the very finest frame builders and painters in the country. Plus, he's a really great guy. I've known Brian casually for several years, having many mutual friends, and he is now running a restoration company. Check his website for details for repair information; www.vintagecyclestudios.com.
I hope that helps.