A practical guide to finding which modules of a trained LoRA cause a specific defect (blurry skin, lost identity, ignored pose) and to fixing it without retraining.
Everything here is post-hoc weight surgery: you take a .safetensors you already trained,
produce variants with some module groups zeroed or scaled, generate with each under a fixed
seed, and measure. No GPU training, minutes per iteration.
Worked examples at the end come from two real LoRAs on Qwen-Image-2.1 (a head swap and a