finding a tester for the hipot tester

Hello, we repair analyzers and hipot test every unit.  We send the hipot testers out for calibration every 6 months.  We just had an incident where the calibration had failed and we could have recalled a bunch of analyzers.  I would like to find an off the shelf tester that will verify the the hipot tester is working properly every day.

Any suggestions would be appreciated!

Thank you!