Since the movement may contain lubricants that have hardened, a special solution is used which helps to change this state. The special solution also helps in dissolving any dirt particles that might have accumulated inside the movement. During this stage, all worn out parts and seals, including the winding crown and the case tube, are replaced with genuine Rolex parts. 4. Cleaning and Polishing: The Oyster case and the bracelet are cleaned and hand-polished. The bracelet also receives repairs for any worn out part, disjoint links, or other defects. To maintain the same standards that Rolex follows while making these watches, the Rolex Service Center cleans and polishes the watch using advanced ultrasonic technology. 5. Series of Quality Control Tests: Once your Rolex receives a thorough cleaning, polishing and servicing, it has to pass a series of rigorous quality tests such as pressure proof test and the timekeeping test. The pressure proof test is conducted on the Oyster case without the movement inside. A special tank, called a "Mariotte" meter and equipped with high tech electronics, is used for this test. Inside the tank, a vacuum air-pressure is created to test the watch at its guaranteed depth. A similar test is also conducted during the making of Rolex watches at their premises. As a direct consequence, once you service your Rolex at a Rolex Service Center, you can be assured of receiving rolex the same quality in your watch as a brand new Rolex exhibits. After the watch passes the pressure proof test, it is installed with the movement, re-lubricated and tested for accuracy in timekeeping. If it shows any minor deviations, a special Rolex device called the "Microstella Tool" is used to make micro adjustments to correct those deviations. Once this test is also cleared, the watch is prepared for a final pressure proof test in the Mariotte meter vacuum tank. 6. Final Quality Check by an Expert: Before handing over the rolex watch to the customer, an expert technician makes a final quality inspection to ensure that the watch is free of every possible error, both in appearance and in operation. Every Rolex Service Center charges overhauling or servicing fees from the customer if the servicing of the watch does not fall in the warranty period. Once the servicing is done and the payment received, they issue a one-year warranty on the serviced Rolex. This warranty is accepted at every Rolex Service Center located across the globe rolex . It is not recommended to go for the complete overhaul every time you take your watch to a service center. Often, the condition of your watch only requires partial servicing in the form of replacement of crystal, stem, crown or dial refinishing.