I have several SR1 resistors in good condition that I purchased through eBay, originally from an OSHA laboratory, where they were treated well. The screw-in gold-plated banana plugs are also in good condition.
The manufacturer's dates are 1977, and the last OSHA calibrations were done in 1978. I would like to get newer measurements on three units: 1k, 10k, and 100k.
Can anyone speak from experience on the longevity of these units, and what an independent calibration lab (in US) is likely to charge for measurements to the original tolerance (0.001% = 10 ppm)?