What is a CTR?
CTR is an abbreviation for Complete Technical Revision; it is also sometimes referred to as a Complete Service or Overhaul.
A Complete Technical Revision is the main process by which a watch or clock is serviced, and involves the complete disassembly of the internal mechanism, ultrasonic cleaning of all components, pivot polishing as needed, re-assembly, lubrication, testing, and final timing adjustments. The replacement of damaged parts also occurs during this process.
Since access to many internal components is limited without full disassembly, most parts can only be replaced during this process. A CTR is considered a major repair, and the price and time it takes to complete depends on the brand and complexity of the mechanism.