The fan on my Worcester 240 combi RSF will not start up half the time. The strange thing is that is you check the brown wire going to the motor on the fan with a volt meter you first get 240 volts then nothing and then the boiler will work. I think that the motor in the fan is on it's way out as both circuit boards have been changed which didn't resolve the problem but the electrical test get's it working for a short time. Has anyone had this problem as I don't want to change the fan and find it something else.