To determine the coordinates for the final stage use the GRID ,ROW ,COLUMN formula below.
Inside there are banks of boxes lining the walls separated by black trim like a grid pattern.
The grid is upper left corner, rows are down, columns are over, this gives you a number that you use.
N 28 16. [ ( G1811:R6:C5 ) - ( G1391:R4:C6 ) + ( G591:R3:C4 ) ] W 82 42. [ ( G1011:R5:C4 ) - ( G291:R5:C6 ) - ( G171:R2:C6 ) ]