Partsconnexion has lots of diy parts. I am sure there are others as well.
http://www.partsconnexion.com/
An easy upgrade would be tubes. Try Andy at Vintage Tube Services. Upgrading my tubes was like getting a new piece of gear.
http://vintagetubeservices.com/
http://www.partsconnexion.com/
An easy upgrade would be tubes. Try Andy at Vintage Tube Services. Upgrading my tubes was like getting a new piece of gear.
http://vintagetubeservices.com/