The click on part (yellow)of the handle inside the robot is broken on one side and makes the handle loose.
How can I buy and easily replace that part ? Many thanks in advance for your help.
ANSWER: The HANDLE LOCK may be purchased in the U.S At Aquatic Distributors. Here is a link to the parts page. Bravo Parts List
The image above is their parts diagram, however the handle lock appears to be incorrectly labeled. It is #20 on the parts order list. The side plate should come off with several screws. Let me know if you have a problem.