Hi there, it's Jack at Dyson.
I'm not sure from your question how you're testing the suction at the cleaner head. For safety reasons we'd strongly advise against placing a hand underneath the cleaner head. This is not a good way of testing suction - the soleplate needs to form a close seal with the floor surface for high pick up. It's normal for the suction to feel stronger through the wand and through the cleaner head inlet as the suction is concentrated over a much smaller area.If you place the cleaner head on a sheet of newspaper, then run the machine with the brush bar turned off, you should see the newspaper sticks to the cleaner head, as it's able to seal with the soleplate.
You might also like to take a look at our online Support guide, to make sure there's nothing blocking the machine which you may have missed: http://www.dyson.co.uk/support/dc25/dc25-multi-floor/my-machine-is-not-working/machine-not-sucking-picking-up-as-well-as-usual/how-to-wash-filters/check-suction
If you have any further questions, it would be worth giving our freephone UK Helpline a call to run through some diagnostic checks with one of experts. You can reach us on 0800 298 0298 - we're on hand to help from 7am-10pm, 7 days a week, and calls are free from UK landlines.
Dyson Online Customer Supporthttp://www.dyson.com