Tube tester for calibration

Where can I send my B&K 707 tube tester for calibration. I live here in NJ.
Please advise.
All my 6922/E88CC and 7308's are reading below the acceptable range using the jet switch mode? Do these tubes happen to give low voltage count? My 6DJ8's are okey using the switch mode of this tester.
I have no experience with this guy . . . I just found him on the internet while looking for tube testers. He apparently sells refurbished testers. Might be worth a call.