A common shop repair is fixing spindles in a chair that have loosened up. When the end of the spindle is too small for the hole, a good fix is to simply wrap and glue thin veneer around it. To hold the veneer in place while the glue dries, use an automotive hose clamp. Once done, you can either rebore the hole or shave the spindle end for a snug fit.
It’s possible to retrofit insulation into an existing home, even without the access provided by remodeling. The choices, however, are much more limited. There are some retrofit insulation products that are designed for minimal disruption to finished wall or ceiling surfaces. Significant gains in R-value, however, may mean hiring a professional to assess your needs and devise an energy savings plan. Small or large, insulation projects can yield substantial gains in R-value and in comfort.