A lift assembly comprises a base, a drive mechanism, first and second flexible drive elements driven by the drive mechanism, first and second sheaves directing the first and second drive elements in different directions, and first and second load cells sensing load on the first and second sheaves. The sheaves can be mounted to first and second sheave mounts, and the load cells can sense load on the first and second sheave mounts. The sheave mounts can be provided on first and second sheave plates, and bearings can be positioned under the first and second sheave plates. The lift assembly can further comprise first and second sheave brackets for coupling the first and second sheaves to the first and second sheave mounts. The first sheave plate can further include an opening, and at least a portion of the second sheave bracket can be positioned in the opening.