During inspection, a rear monoshock is found to have oil coating its shaft and dripping from the lower mount. What is the correct repair procedure?

1. Tighten the spring preload adjuster collar to compress the leaking seal
2. Spray the shaft with silicon lubricant to seal the leak
3. Clean the shaft and refill the damping fluid with heavier grade engine oil
4. Replace or rebuild the shock absorber assembly, as the main shaft seal has failed