Burning smell after replacing brushes Zanussi ZWH6140P

Bought my machine in 2011 and use it about twice a day. A week ago it started making a cracking noise when spinning and a local chap came and said the brushes were worn. He replaced them and it worked fine for about 4 washes and then we noticed a burning smell. He came back and said there was some melting on the brushes and a couple of other customers had the same issue, so they thought it was a dud batch of brushes. Now two days (and about 7 loads) later, the burning smell is back. Just wondered if anyone else had come accross this. We can get the brushes replaced again, but I want to be sure its not a bigger issue that could cause a fire etc.