Wood in stringers??

[crsavage1]

I opened the top of one of stringers to see how easy the wood would come out with the plan being to foam the stringers back in, the wood isn't really budging. Without chiseling it out, or opening the stingers from the side, it would be pretty difficult to get the wood out. There is a significant void in the stringer as they are much wider than the original wood. I could foam that in?

Or like I said, I could cut open the stringers from the side as I did the one and get the wood out?