We have seen a lot of issues with Python Service not being available. There are a lot of factors being account for this such as the RAM and memory of the machine, the complexity of the environment, the usage of the services, and most important environment meeting the system requirements prerequisite.

We have seen a lot of customers creating python services with other services(Automation Service or Webplayer) on the same Node manager which is not the recommended or supported configuration.
It's an absolute requirement that each Python Service (PYSRV) instance and each TERR Service (TERRSRV) instance must be installed on its own dedicated node and server, not shared with any other Spotfire service or any other application. It's particularly important not to try to make PYSRV or TERRSRV share a node and server with the Web Player.  In a competition for server resources, the Web Player typically wins, and that interferes enough with PYSRV and TERRSRV to make them unavailable.

The following notes are included in the system requirements for PYSRV and TERRSRV:
"Important: Do not install Spotfire Service for Python on a node with other Spotfire services."
"Important: Do not install TERR service on a node with other Spotfire services."

This article will help you to get an overview why we get this frequent errors

Doc: TERR

•  https://docs.tibco.com/pub/spotfire/general/sr/sr/topics/tibco_enterprise_runtime_for_r_SE_1_12.html

Doc: Python

•  https://docs.tibco.com/pub/spotfire/general/sr/sr/topics/spotfire_service_for_python_1_12.html