[RodB]

Hey guys, logic tells me that if the transformer primary resistance measured 1300 ohms then the center tap to each end wire will measure about 650 ohms. If you don't measure any resistance on one of the leads then it's an open coil. It's possible that the wire lead has disconnected from the coil wire and can be easily repaired.

You don't have to match the resistance of the primary to a replacement transformer. A replacement transformer primary will need to have an impedance close to the plate impedance of the output tube and a secondary impedance to match the speaker. You will also have to use ohms law to calculate the power requirement of a replacement transformer. You can find charts online that match the tube with opt.