[Mondial]

The best solution would be to repair the existing choke if possible. If not, any high inductance low current choke will do. There are only a few milliamps passing through it. The purpose of the choke is to remove AC ripple from the detector plate supply which is very sensitive to hum. With the resistor replacing the choke you may notice a increased hum level as a result

You can also try a much higher resistor as a replacement. The value is not critical and you might try values in the 10K to 27K range to provide increased filtering and lower hum levels.