Quite a common fault, I've had this several times with this and some other Technics models.
It's almost always due to faulty fan motor. This can be verified by measuring the resistance across it. (Should read between 20 and 30 ohms).
Only the original fan type should be fitted.
There are a few other checks an engineer will make.
Cost should be around £50-£60.
Cobweb
February 2007