converting letters to numbers

This was really close. However the "D"s and "F"s for some reason code back to the two first columns (unless I did something wrong).

Please see the attachment for more clarity.

I need the "D"s and "F"s to hold the value of the previous cell (example: so column "U24" has an "F" value in the top table, therefore in the bottom table it should have the value "51" because the last progressive value, in the top table, was "C" in column "T4", which provided the corresponded value of "51" in column "T24"-- same for column "N24" which should be "32" in the bottom table to correctly correlate with the top table where in column "M4" has a value of "A" so in the bottom table column "M24" has a value of "32" to correspond with the middle chart).

Does this explain better? The formula in the bottom table needs to be able to recognize that when a value of "D" or "F" is present that the numerical value in the bottom table cannot advance beyond the last given number for that row, until a value of "A"/"B"/"C" is given in the top table (and when "A"/"B"/"C" is then given, the new value in the bottom table must correspond correctly to the middle chart).

Thank you for you assistance.