Is there a better method when cutting installed 105 wood siding?

[12 point]

I'm working on an older house with 105 pine siding. This is the type where the top edge (tongue) is thinner than the rest of the siding (3/4) and one piece slightly overlaps another. The bottom edge has a rabbit the entire length that allows another piece to slide up under the other.

Several years back, I had a lot of siding milled at a lumber yard out of sixteen foot long beams. If you've ever tried to replace old 105 siding with new siding from the lumber supply stores, chances are that new siding is not as wide and the cove profile is different. This is why I had the siding custom milled. And, yes, it was expensive.

Here's my issue. About 12 years ago, I was doing a remodel project and replaced several board feet of rotten and storm weathered siding with new.
No matter what I did to make that new siding last, I will have to replace some of it again due to rot. The majority of the pieces of installed siding is twelve feet in length and only small areas have damage that needs replacing. My standard method when replacing is to use a circular saw to cut a kerf into the siding along the middle of a wall stud. First, I remove any nails in the way to avoid damaging the saw blade. WIth this style of siding, I need a method that would prevent having to cut into the other siding above in order to cut out the damaged area.

Am considering using a Dremel with a small diameter straight cutting to bit to finish cutting the tongue area where the circular blade of the saw can't reach without cutting into good siding above.

Sorry, but I don't have any pics.

If you know what I'm talking about, do you have any suggestions or a better method to cut installed 105 siding?

It's not feasable to remove an entire twelve foot section of siding when only a foot or two of it needs replacing.

[Txpepper]

Find a freight harbor and get a little tool called a multi purpose tool with the straight cutting blade on it. I use on on the job all the time and I love it. They cost about $20. That will do what ya wanna do. It flush cuts great.

[Txpepper]

Where are you located?

[Txpepper]

This is what ya need.

[Bowstrider13]

You could remove the 12' section replace with new and keep good old ones for future repairs

[12 point]

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This is what ya need.

Thanks. I had thought of the oscillating tool, but couldn't justify the price of a Fein or Bosch.

Your suggestion will fit/work for sure.

[12 point]

You could remove the 12' section replace with new and keep good old ones for future repairs

That's not a bad idea, but when there is the chance of damaging the long section more when removing it, than would occur from cutting out the small damaged area, it is sometimes easier to just do the latter. I had to use ring shanked nails when I installed new boards 12 years ago. Those nails really do well what they're designed to do. They hold things down tightly.