The original get_text_value function was only considering the first and last character of the entire string rather than evaluating each individual word. To correctly calculate the sum of the values corresponding to the first and last letters of every word in the input, the string must first be converted into a list of words using split(). Then, for each word, its first and last characters are matched to the predefined letters list to find their corresponding numeric values in letter_values. These values are summed and accumulated to compute the total text_value. By modifying the loop to iterate over each word instead of each character, and by properly indexing the first and last letters of each word, the function achieves the intended behavior of computing a sum based on all words in the input text.