How to replace a character in a string based on its position

Hi,

I am having isues trying to replace a specific character in a string based upon its position, for example in the following string:

C.R.P.R.L.C.K.H.C.R.X.R.L.F I would want to replace the 9th character (L) with “N”.

I have been messing aroung with String Manipulations and Column Expressions and I can identify the 9th character easily enough, but I am struggling to replace only that character in a manner that would be automated and reproducible over many different strings.

So I was hoping some members of the comunity might provide some inspiration…

Thanks!