Find all instances in formula string
 

I can do this manually faster than I can get an answer back and write the
code, but for future reference -

I set formulas such as:
=AVERAGE(sht40Fcol10 rngT5, sht40Fcol10 rngT6)
in sequential columns (so the col10 formula in in Col. J, col11 formula is
in Col. K, etc.)
(Thank you, Tom Ogilvy!!)

These work great. However, in inserting and deleting cells, I find the
above formula is now in (for example) col12, and the formula for col11 in
now in col13, and so forth.

Is there an easy way to find and replace the column numbers? Even more than
one instance in each formula string?

Ed