The answer to 'hydro jetting not working' is that there can be several common causes, including a clogged or damaged sewer line, insufficient water pressure, or an issue with the hydro jetting equipment itself. Symptoms may include slow draining sinks, toilets, or tubs, gurgling noises, or sewage backups.
Some potential solutions include checking the hydro jetting equipment for any clogs or damage, ensuring the water pressure is adequate, and trying the hydro jetting process again. However, if the issue persists, it's best to call a professional plumber who can properly diagnose and address the problem.