Portland District closed The Dalles navigation lock May 24-26, 2011, to repair a gearbox that operates the mechanism for opening and closing the north leaf of the downstream gate. The initial assessment was that one or more bearings in the gearbox were failing, which could lead to more significant damage to other gate components and an unplanned, extended repair outage. However, damage to the bearings, gears and shafts was less than anticipated after the gearbox was opened, drained, disassembled and cleaned. his maintenance should allow the gearbox to function until it is replaced during the next regularly-scheduled maintenance outage in March 2012.