I'm having trouble getting the Json Input step to run when used in a Kettle data source.
There is mention of something here about non-compatibility with 6.1 as i gather than the fastjson code is now part of the core plugin?:

I have used the revised jar from here and it works in spoon/report designer, but both this and Json input fail when i try and run the report from the biserver-ce.
I get an error "Transformation reported 1 records with errors and stop-on-error is true. Aborting."

I have reverted to using a Modified Javascript step which works, but is prone to scripting errors (and I gather is slower).

I'm running BI on Tomcat 8.0 on my local windows machine and I copied across the Jars from the data-integration/plugins folder to the biserver-ce/pentaho-solutions/system/kettle/plugins folder. So for example both the kettle-json-plugin and fastjson-plugin folders and contents are present.
Any suggestions on what to check?