Using data extracted from the NOAA website the RLR diagram has been re-drawn. Primary benchmark appears to be 7624 F 1979 3.917m above gauge datum. This benchmark appears in Epoch 1960-1978 and 1983-2001 with the same levelling value. The benchmark BM7 2.429m above gauge datum appears in the early Epoch as NO 7 1950 again as 2.429m relative to the datum but does not appear in the 1983-2001 Epoch.
Documentation added 2015-02-23
NOAA website confirms that the station was removed in September 2003.