Suntour are mainly an OEM maker of forks, which are normally found of lower end bikes, the XCM fork you have falls into this category. If you have been running them for six months, without having them serviced they could have issues with the blushing , seals or stanchions (Suntour forks do seem to wear excessively here), the best option would be to take it to the shop where you got it from to have it serviced.

The biggest problems with having these serviced, is availability of spares and the cost of getting them serviced, which could be more than a new fork. Have a look here for similar questions and answers which may help you http://www.bikeradar.com/forums/view...php?p=15718276