The first things to look at are the oil temp and the steel temp. Parks #50 is used at room temp. It will not harden fast quench steels like 1084, 1095, and W2 properly at 130F.
Second, make sure the steel is at the desired temp. How did you determine the 1575/1500/1475F? If it is the readout on a HT oven, then do a check to see that the oven is reading properly.
Third, are you sure it isn't hard. I get an email almost once a week from someone who has normalized and quenched a blade that a file still bites. It may Rockwell test at Rc55. I tell them to grind off 2-3 thousandths all over the blade and then test again. Nearly every time it is hard beneath the thick layer of decarb.
The steel condition could be a problem too. I would do the first cycle at 1600F to 1650F and then do the 1575/1475. Fully spheroidized steel may need significant normalization to get back to a hardenable state. I would suggest you quench the steel from the 1575 step iof you have been having problems.
This is where a double/triple quench has advantages. It allows all the steel to convert to martensite and pearlite on the first/second quench, and then to convert to finer grained martensite on the second/third quench. I usually quench my steel on the second step of normalization, followed by the final austenitization and quench.
Here is what is happening:
In the first heat to 1600+F, the steel fully dissolves the spheroid structure and puts everything back into solution. Upon cooling (fast of slow) it converts into a normal structure (pearlite on a slow cool and martensite on a fast cool). If doing only one step before the final quench, it is best to quench this step.
The second cycle takes the newly formed grains and puts the carbon back into solution to form FCC iron-carbon bonds. Upon the quench from this step, the structure will form BCC martensite in a fine grain. If doing a third step, this step prepares the steel to a fine grain structure and proper condition.
If doing a triple quench, the second step has refined the grain, and the final quench just assures the temperature and all else is right for a final fine grain martensite to form upon cooling.
On your blades, I would re=austenitize the blade and quench from 1500F again. I bet it comes out fully hard.
