DIAGNOSIS It's almost never broken out of the box. The most likely cause is that one of the suction control settings is engaged incorrectly, or there's a simple setup oversight.
FIX First, check the suction slider on the handle—make sure it's pushed all the way forward to the "max" setting (the little pictogram of a carpet). Next, verify the dial on the canister itself is turned fully to the highest setting (usually a "6" or "max" symbol). Also, ensure you're using the correct hose port on the canister; some models have a dedicated "powerhead" port. Finally, confirm you've installed a new bag correctly—the seal needs to be intact.
IF THAT DIDN'T WORK Check for a transport lock or protective plug that wasn't removed. Some models have a plastic plug in the hose socket or a clip on the wand that restricts airflow for shipping. should show if yours has one.
HEADS UP Using the wrong bag type or a non-genuine bag that doesn't seal properly is a huge cause of perceived suction loss. Stick with Miele bags for this model.