My 40-yr-old home has an annoying squeaky spot under the carpet in one
area. When I was in the crawlspace insulating the water pipes, I noticed
a place in the same general area as the squeak where one cross-brace
"leg" had become unattached from the joist. Could this be causing the
squeak? If so, would just nailing it on again fix the squeak, or should
I put some sort of shim between the floorboard and the joist first?
Joists are 16" o.c., if that matters.

Thx.