Indeed we do. Found schematic on net for your p/supply. L504 is merely an inductor. It is used in series with L503, also an inductor,on the dc side of the bridge diode, perhaps because they use only a 100uF main filter - false economy. You could probably bridge out the 2 pins with continuity for test purposes and check if the set starts without tantrums.
No idea where you'd get a replacement (ebay??) but as it is a filter choke only, you may be able to find a coil that does the same job in your box-o-bits.