Pavao,
There are two types of service for the D9.
Battery Service - Replacing the battery compartment o-ring and battery. After the service, two standard tests will be done.
2 Year 200 Dive service ( Full Service) - The D9 will be disassembled down to the case. An internal and external cleaning will be done to all of the metal parts. All of the o-rings inside of the unit, as well as the battery will be replaced. After the service, two standard tests will be done.
The two standard test that are performed after each service are as follows:
The first test is a pressure test which will test the integrity of the computer. The second test is the function test. The computer will be dove in a pressure pot to check that all of the functions are working properly.
The 2 Year 200 Dive Service is highly recommended by Suunto to be performed every 2 years or 200 dives, whichever comes first. Whether the computer is sitting in a drawer or being used every day, this service is recommended to be done following those guidelines.
As far as the Gekko, the only service that can be done is a battery service. The Gekko is a sealed unit, so internal o-rings are not able to be replaced.
If you have any other questions please feel free to ask.
Best Regards,
Chris from Suunto