The issues start with turbine unit 2 where it has encountered a problem for a long time before the accident in 2009. The problem first appeared after installation in 1979, after that during year 1980 to 1983; there many issue and problems related with seals, vibration of the turbine shaft, and bearings arise.From late March to late November 2000, the complete recovery turbine 2 was performed. Cavities up to 12 millimeters (0.47 in) and cracked up to 130 millimeters (5.10 in) long was found in the turbine wheel and repaired. Many other defects found in the turbine bearings and subsequently repaired. In 2005, repairs were made to the turbine 2. Problems encountered are similar in some aspects to the defects observed during previous repairs. From January to March 2009, turbine unit 2 was undergoing scheduled repairs and modernization. It is the first and only turbine in Sayano–Shushenskaya hydroelectric power station that equipped with electro-hydraulic speed regulator supplied by the Promavtomatika Company. During the repair, turbine blades were welded, because after a long period of operation, cracks and cavities have emerged. Incorrect turbine wheel rebalanced after this repair.