(Kit #1) is a single sense electrode (one wire to the electrode, applicable to S/N above 920500001), (Kit #2) is a dual sense electrode (two wires to the electrode, applicable to S/N below 920500001).
Note: Limit switch 231626 is no longer available and currently there is no replacement
Tune-Up Kit #1 Contents (links in blue)
Tune-Up Kit #2 Contents (links in blue):
Click The Down Arrow To View NT-24SP Exploded Parts View Links