We have an esse sovereign oil range. According to the last owners of the house it hasn't been used for several years and now that we have tried to use it we are getting no oil to the burner pan. We have oil in to the BM control unit but non coming out of the control unit. I have checked the safety lever and the filter. There is oil inside the BM control unit. The control knob on top of the unit does not seem to have any resistance when it is turned. I have blown through the pipes, both inlet and outlet and there doesn't seem to be any blockages.