Vinyl Blind Stops?

Once you get really good with a Mulitmaster type tool with a fresh precision wood blade you should be able to make that cut in place. I've done it many times. You just have to take your time and watch out for any trim nails that will kill the teeth on those expensive blades. I'm assuming that this in a painted stool so a nice bead of interior caulk will cover any minor slips.

Are you suggesting a multifunction tool (I have the single speed Harbor Freight version) for the entire cut?

Would you forgo the circular saw plunge cut?

I know that the saw shoe will limit the length of my circular saw cut, but if I rig up a straight edge guide, then at least that portiion of the cut will be "perfect".

For what it's worth, when I was investigating the situation the other night, I had no problem wiggling the stool up and down. I know that that doesn't mean that it'll come out easily, but it certainly isn't rock solid.

Of course, I am also very aware of what often happens once you start taking stuff apart...

BTW - yes, it's a painted stool so there will be caulk involved.

Update:

I cut the stool in place. Plunge cut with my circular saw for as much as the saw shoe would let me, and then finished off the corners with my multifunction tool.

It came out quite nice. The very small gap will easily be covered with caulk.

As far as my original request for 1/2" x 3/4" vinyl blind stops, it's a good thing I never found a source for them. That was not even close to what was used on the original picture window.

Turns out that they nailed 1 1/4" x 3/4" stock to the exterior face of the frame and then nailed the brick mold to the front of that, leaving a 1/2" reveal as the stop. I used my multifunction tool with a wood/nail blade to remove it so I didn't have to mess with the aluminum wrapped brick mold.

I then ripped some 3/4" x 4" vinyl stock as replacement stops which I'll glue into the slot with silicone adhesive tomorrow. As it is, the vinyl is tight in the slot and perfectly straight.

Rough work all done for the day, finish work to be completed tomorrow - while I watch the Bills beat the Skins in Toronto.

Thanks for all the suggestions.