Finally managed to get a workaround. The SAP note solutions used the old Visual Administrator, subsequently replaced by Netweaver Administrator after v7.10 (I am on 7.11). Could not find any "simple" description of where the Security Provider/Policy configurations are under NWA but eventually found Services under Assigned Actions of the Roles in Identity Management. Found all the jms.default entries (assume these are same as service.jms.default.authorization mentioned in the SAP note) and assigned these to a new role which I created. I then assigned the new role to the user Guest and the scheduled jobs are now running correctly. Don't know if this is the correct solution but it works.
The username/password on the scheduled entry definition seems only to be relevant if running the job directly. When it runs as a scheduled job it always seems to run as user Guest.
