Dimplex CLB20L Club Mid-size Heater

well, we've had ours about two years. As time has gone on the thermostats have become more and more sensitive. Initially it would cut out after 30 minutes of being on 2kws. In the last year thi has gone down to 10 minutes. Also, the motor which drives the optiflame has begun to make an awfull noise at start up - this also started about a year ago.