my hoover (u3495001) cuts out after 10 mins of use ?

Since i bought this hoover just over a year ago i have had this problem where after 10 mins or so when the motor gets warm it cuts out. I took it back after about 1 month of purchasing it to the shop who told me it was because the bag was too full. Although i didnt think it was i took it home replaced the bag but the problem still remained the same. The second time i took it back they told me the filters were dirty and needed replacing, again i didnt think this was the problem but i took it home and changed them but the problem still remains.
The warranty has run out now so i carnt take it back(not that taking it back when it was in warranty was worthwhile) has anyone any other ideas as to what the problem could be
thanks Mark