If the other rooms don't bounce it makes me wonder if some of your joists are damaged by cutting by the hvac guy or termites. I'd take a close look and replace anything that is compromised before moving ahead with the blocking. The blocking depends on the integrity of the blocked joists for its integrity.

PM me if this doesn't make sense.

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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.