Hi Andy,
I don't get enough info from the instructions. Can you please kindly give a hand on runing ur_sim?

1. You've got pkgs ur_gazebo and ur_description in your ur5_sim. Do I need to delete the pkgs with the same names which I installed before in ROS on my PC?

2. Do I still use the following command lines to run ur5_sim? If not, can you please elabrate? (I tried it this way and it throws errors)

roslaunch ur_gazebo ur5.launch limited:=true
roslaunch ur5_moveit_config ur5_moveit_planning_execution.launch sim:=true limited:=true
roslaunch ur5_moveit_config moveit_rviz.launch config:=true

3. How shall I use the following command line in ReadMe? first time using this type of file.

./ur_gazebo/scripts/gazebo_starter.sh

My last question is in the link shared in Readme on how to To use with the SpaceNavigator, disable Gazebo's link to the SpaceNavigator:
Can you please take a look at this? I assume the first solution does the work. But how exactly does it mean by saying Just change the topic to something you are going to listen in your own plugin and it will not interfere with the gui, which listens to ~/spacenav/joy
How shall I modify the following line:
topic=~/spacenav/remapped_joy_topic_to_something_not_used

I'd never ever forget your kindness and constant help. I am kind of alone on ROS in our team. Thank you so much for your support. Thanks with no end.
Best regards!