You might want to re-initialize a node for the following reasons:
An updated version is available for the build agent. This is indicated by a red exclamation icon in the Agent Version of the Node.
You made some changes to the node manually and it is no longer picking up jobs
The node isn't picking up jobs and seems 'frozen' for some reason
To re-initialize a node:
View the node as described above.
ClickRe-Initialize. This action will initialize/install everything from scratch.
If your nodes were not initialized automatically, you will need to re-download the initialization script and run it on your node manually.