We propose a low-cost torsion balance experiment to test the quantum gravitodiamagnetic framework published by the Hunan group (Physical Review D, 2024-2026). The target signature is a repulsive force that appears only when a YBCO superconducting disk is rotating at 77 K, facing a passive mass. If detected, this force would be unambiguous — no known force (electromagnetism, Newtonian gravity, Casimir forces) produces repulsion synchronized with superconductor rotation. The experiment costs USD 1,360-1,710, takes 3-4 months, and requires only a torsion balance, YBCO disk, brushless motor, laser pointer, webcam, and liquid nitrogen. No lock-in amplifier, no microwave source, no vacuum chamber. Results are publishable regardless of sign: a null result establishes an upper bound, a positive result would open a new experimental field in quantum gravity. This document is part of a three-document series. Companion documents: full technical proposal (Doc2) and plain language research summary (Doc3) available in the same Zenodo repository. Version 5.0 (June 2026): Revised edition. Removed section on UAP flight characteristics and references to classified testimony. Removed DIA report from references. The experimental proposal now stands on its own physical and theoretical merits. References to Podkletnov and Fetisov removed. Recommended publication venues added for both null and positive result scenarios. The physics and experimental design are unchanged.