This will happen if you overload the machine. If it isn't that, rotate the empty drum and check if there is any undue movement or noise, if so, may be the bearing going. Failing that, take the top off and check the the concrete weights and the supporting struts and springs are still firmly attached to the drum and the machine casing.
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