Smelly Washing Machine

I am having a problem with my washing machine and wonder before I buy a washing machine if there is anything I can do? I have taken off the outlet pipe, I also had the pipe to the pump off, but I couldnt see a problem with these. I think that the smell is coming from the drum! Whatever I try and do the smell will not go away and there does seem to be some mould inside. I'm wondering if something has got into the tub somehow but there has never been a problem emptying it. If there is a solution to this washing machine problem I would love to know before I buy a new washing machine. 

Thanks Perry