That first, 13-episode season from 1979 initially gave the impression to be a Boston-area curiosity, accessible only to native residents via WGBH. But it struck a chord with viewers, virtually 250,000 of whom tuned in each week to observe the titular house—a Victorian in Boston’s Dorchester neighborhood—undergo its gradual metamorphosis. The surge of curiosity allowed This Old House to vault into the primary PBS lineup a 12 months later, the place it has remained ever since. What could’ve been framed as a melodramatic battle of the wills is instead offered as a teachable moment between the tradesman and the homeowner.…