Mark is correct. Great Plains Audio is the only place to get proper repair for any vintage Altec loudspeaker products. When Altec's Oklahoma factory closed, they sold off at auction a lot of the equipment for the manufacturing and repair of their products. GPA purchased a lot of the speaker department equipment, and a lot of the electronic equipment went to Ira Rostampour at IraTec in Yukon, OK. Just like GPA does for speakers, for old Altec amplifiers, no one does it better than Ira to get them back up and running at or beyond original factory specifications. In case any of these guy's websites aren't operational or up to date, let me know if you or anyone else needs their contact info. I have a significant amount of vintage Altec equipment, and I would never use anybody but these guys. These guys are friends of mine, so I'm biased, but it's the truth!
-Brad