[MrFixr55]

Ohm the coil. If the primary is out, it could be that it took a lightning hit. You might be able to replace the antenna coil with a loop antenna from an AA5. You stated that touching the grid cap of the first detector gives you a good signal. What happens if you touch the grid cap of the RF Amp tube? If no signal and the tube is good, the primary of the interconnect transformer between the RF and 1st detector could be bad, likely an open primary.