Non-metal parts, such as plastic gears, are increasingly being used in modern instrumentation and mechanical engineering. Such gears have a number of advantages: quiet operation, low weight, relatively low manufacturing cost and so on. Nevertheless, even in case of short-term exceeding of design loads their complete or partial destruction can be observed. In the case of failure of the mechanism is associated with downtime of technological and other equipment, it is necessary to minimize repair time. Time of repair depends on complexity of the mechanism, as well as the time of receipt of serviceable part for replacement, which can exceed one-two weeks. In case of breakage of simple parts, there are special groups of workers, who are able to design and manufacture a damaged part for replacement by themselves. It is advisable to expand the range of parts, the quality repair of which can be carried out directly on site. In the case of broken gears, modern additive technologies can be used for this purpose. It is worth noting that the problem under consideration is quite extensive, as its solution depends on the degree of destruction of the wheels, the possibility of using polymeric materials with equivalent mechanical characteristics, operating conditions and other. This publication deals with the issues related to restoration of gear transmission serviceability with the use of 3D printing. The problem of identifying the geometry of the gears when replacing one of the pair, the choice of technology and material, as well as ways to increase the load capacity of the transmission are explored separately. This work will be of interest to developers of 3D models of gears and specialists associated with the repair of gear mechanisms made of plastics.