[Test-Equipment] DC calibrators

[DON CRAMER]

How practical is it for a hobbyist with a lot of meters (3.5 to 6.5 digits) to own an older DC calibrator, such as the Fluke 335D?  How are parts availability and documentation for them?  Do they require support equipment or fixtures which are impossible to come by?  Are they too finicky to have in anything but a professional cal shop?  Do they tend to maintain accuracy over periods of years or do they require routine calibration themselves?  Are they too old to receive calibration?
Don Cramer
Beaverton, OR