You can test your transformer,but only if you have a basic knowledge of electricity. 3000 volts is no fun to get hit with(although it probably won't kill ya). Your clock is a glo dial,the clock face has been painted over.go to Neonclock.org and you can find many pictures of them,probably advertised a company,and many also advertised radio stations.
Antique Neon and Advertising Clocks is my page on Facebook,and we have members there that can supply you with any parts you may need,including a new face for it.. I'm actually working on mine right now.https://youtu.be/HHHtBW8mGkI