I believe this benchmark, and others that are along this former railway are all missing/gone. (NE0390, NE0391, NE0392, NE0393 and possibly more). This track was removed a few years back, and is now nothing more than a foot trail.
I could still be wrong, but I looked all over the south side of the track. GPS was leading me to the edge of where the taller grass starts to grow. Didn't see any sort of concrete post with the copper peg like the description says.
I'll post two pictures of this area. It's very easy to get to from Crooks Road just before Hamlin. Park in the Vetinerary Clinic parking lot and walk over.