Fisher and Paykel Dryer "ED 56 nz'?

My dryer is very unreliable - it will work with a load sometimes absolutely fine, other times it won't spin at all - makes a grinding noise as if its trying to, maybe even do half a rotation before stoppong. I have tried taking clothes out to lighten the load, even got down to having just a couple of things in it and it still wont work. I've 'pushed' the drum round to get it going - this sometimes works after a few attempts but it is so frustrating! Hope you can help me!