The coupled reaction channels method is formulated as a two-step procedure. In the first step, the eigenvalue problem of the overlap operator is solved. In the second step, an off-shell transformation is applied to the coupled reaction channels equation. The transformed equation has an energy-independent interaction. Redundant solutions which arise when the test function space is linearly dependent, are removed from the physical part of the spectrum and become positive energy bound states at chosen (unphysical) energies. The non-orthogonality of test functions of different channels is related to the appearance of implicit distortion corrections.