I had a bouncy floor in my house. If you want to stiffen it you need a full depth block...In other words, if your floor has 2x10s the blocking needs to be 2 x 10. Diagonal cut bridging is good but the attachments might have gone weak on you.

At my house we cut the blocking and screwed it in with about three toenail screws each side. I believe we glued it too. Made a big difference. It has to go all the way to the wall. In this way it forms a beam. It could also be done twice spaced out in even distances.

Do you have enough height to give up for a beam set below?

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.