You mentioned there are two in series? Measure the good one.
You will require a LCR meter. This may be the perfect excuse to get one if you already don't own one. Nowadays, you can find many low cost devices on Ebay or Alibaba. True, they are not precision instruments, but I don't think the inductor value is very critical.
In the position it is attached it appears like a high frequency rolloff. The key factor here is that it should be able to sustain a DC current without saturation. Likely 10 mA or less. That is the reason it is a rod core one.