How to fix the Onan 5500 and 7000 Cummins Generator Surge / Fault Code 58 and/or 14

This is how to fix the Onan 5500 and 7000 Cummins Generator Surge / Fault Code 58 when all else fails.
If you followed other videos advices on how to fix this by cleaning or replacing the carburetor, sparks, fuel filter and oil, (I even fed it fresh fuel from a separate tank), then most likely it is the intake manifold that had a structural failure.
See this video from fellow youtuber: • Fixed! Troubleshooting... and he diagnosed it in these other two videos:
• Troubleshooting an Ona...
• Troubleshooting an Ona...
I documented how to fix it here as I found it really hard to find information on how to change the manifold on KZbin and elsewhere. the part number for the intake manifold is "Onan Intake Manifold 154-3067-03" and it is about $90
From yakimagenerator.com Onan Intake Manifold 154-3067-03 Item# 8679786 - Onan Intake Manifold Gasket 154-3085 Item# 8679787