villager floor

[ron]

I bought a 1964 villager last year in an retirement community here in fl and have felt soft spots in the flooring. At the entrace at the rear and hall, should I replace the area or just pull the carpet and replace the entire floor? Also the bed frame wheels were moving in a downward motion in the bdrm. I have repaired the belly of the beast where there was nothing there. I have two areas to replace yet photos to come if I get it together. Also what product to use, plywood?
Thank You
ron