It stops the case resonating - and that's all that is happening. A quick and safe fix. No need to undo the panel or call someone out. Let the OP decide.
Thanks all. I don't mind removing the panel, done it several times before (I know the engineer code). Will check the screws on the transformer and also make sure the case is securely attached to the wall.
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local