A generator (24) for a wind turbine (1) comprises a rotor (32) with an axis of rotation, a stator and a radial and/or axial locking mechanism. The radial locking mechanism comprises a plurality of radial locks (60) with a fixed portion (70) coupled to the stator and a movable elongate portion (72) configured to move relative to the fixed portion (70) and radially with respect to the axis of the rotation to lock the stator in a radial direction. The rotor (32) may comprise at least one lock engagement feature (86) arranged at its end surface and an end shield (90) located axially outward and at least partially adjacent the end surface. The end shield (90) comprises at least one opening enabling access to the end surface of the rotor (32). The axial locking mechanism may comprise at least one axial lock (80) comprising a removable block (82) configured to partly cover the at least one opening of the end shield (90) and a rotor engagement tool (84) for engaging the removable block (82) with the at least one lock engagement feature (86).