And then I pasted the characters after the lost 10 chars inside the page. Before the characters, I pated the 'w' (since you know you have that), followed the 10 characters lowest possible private keys that still base-58 encode into w........JzXaqU2rcFSoaLaehAQHqoQX1cWCo92tAA3ihLJ7 - replace the dots with 10 "1" (the number one) characters. Because 1 is the first digit of base8 number system. The resulting hex gives the starting range.
This method is
significantly slower than to simply test each character permutation.
You see each character at the start of the string (from left) converts to a much bigger integer than any character from the end of the string. So even the difference between 1 char missing becomes huge.
Take the following example:
Ky**DfuvLpt8eSb8EQzhZwDCQeCaycKeAoxJMY8pfPZXmn3uB38R
Even though only 2 characters are missing the difference between ky11Df... and KyzzDf... as integer is
13491826005831086771641399365157222283117801812915393869332949675679483454208
While the permutations are only 3364.