The answer to 'my shingle replacement is failing' is that there are several common causes, including improper installation, weathering and wear over time, damage from harsh weather events, or use of low-quality materials. Symptoms may include curling, cracking, or missing shingles, leaks, or granule loss. Solutions can range from minor repairs to a full roof replacement, depending on the extent of the issues.
If the problems are limited to a few shingles, you may be able to DIY the repairs. However, for more widespread damage or if you're unsure of the root cause, it's best to call in a professional roofing contractor to inspect the roof and provide the appropriate solution. They can properly diagnose the problem and ensure the repairs are done correctly to prevent further issues down the line.