1. Check the error log for the MySQL 191 instance:

$ sudo tail -f /var/log/mysql/error.log

2. Check the MySQL configuration file for the instance:

$ sudo cat /etc/mysql/my.cnf

3. Check the system resources available to the instance:

$ sudo free -m

4. Check the MySQL process list for the instance:

$ sudo mysqladmin -u root -p processlist

5. Check the MySQL status for the instance:

$ sudo mysqladmin -u root -p status

6. Check the MySQL variables for the instance:

$ sudo mysqladmin -u root -p variables

7. Check the MySQL connections for the instance:

$ sudo mysqladmin -u root -p connections

8. Check the MySQL threads for the instance:

$ sudo mysqladmin -u root -p threads

9. Check the MySQL tables for the instance:

$ sudo mysqladmin -u root -p tables

10. Check the MySQL users for the instance:

$ sudo mysqladmin -u root -p users

11. Check the MySQL privileges for the instance:

$ sudo mysqladmin -u root -p privileges

12. Check the MySQL databases for the instance:

$ sudo mysqladmin -u root -p databases

13. Check the MySQL engine status for the instance:

$ sudo mysqladmin -u root -p engine-status

14. Check the MySQL engine variables for the instance:

$ sudo mysqladmin -u root -p engine-variables

15. Check the MySQL engine connections for the instance:

$ sudo mysqladmin -u root -p engine-connections

16. Check the MySQL engine threads for the instance:

$ sudo mysqladmin -u root -p engine-threads

17. Check the MySQL engine tables for the instance:

$ sudo mysqladmin -u root -p engine-tables

18. Check the MySQL engine users for the instance:

$ sudo mysqladmin -u root -p engine-users

19. Check the MySQL engine privileges for the instance:

$ sudo mysqladmin -u root -p engine-privileges

20. Check the MySQL engine databases for the instance:

$ sudo mysqladmin -u root -p engine-databases

21. Once all of the above steps have been completed, it is recommended to use an automated database observability tool to monitor and fix the MySQL 191 in question. This tool can provide real-time insights into the performance and health of the database, as well as alerting when issues arise. It can also provide detailed metrics and logs to help diagnose and fix any issues quickly and efficiently.