Ampeg V4.com

Main Drag music is a rad shop in brooklyn that I would recommend going to just because they've got a lot of cool stuff and the guys are super nice and very helpful. 
But they also have a really good repair department.  Pat is the guy who does all the amp repair, and he does very good work.   
I worked there last summer doing the amp repair while pat was away.  The shop is awesome.  great work, great prices.