Getting back to Russ.

If you are going to use an outside agency for the calibration/service of your equipment then things to check.

1. A list of the test equipment used on the returned item (for audit purposes).
2. Sevice engineer (print and signature) again for when it all goes wrong (Are they in possession of certification from the manufacturer or are they covered under the companies insurance)
3. Is the company you are using insured to carry out the task.
4. Do you operate a full trust procedure or do you carry out a batch test of equipment returned.
5. Full data access to the tests carried out (Flow/occlusion graphs with time/date of test).
6. If a repair has been carried out, have they used oem parts or third party. Also whats the warranty on the repair.

Its a minefield, good luck.