We run this job out of Stamford, about 6 miles from Greenwich, so there's no local branch or drop-in counter here - a call sets up the visit and we bring the parts with us. Because so much of the housing stock in this part of the area shares that same 1955-1984 build window, we generally know what hardware we're walking into before we knock on the door, which saves a diagnostic trip in most cases.
Winters here fall into the colder, more severe end of the regional climate band, and cold makes old steel rollers worse before they get better - the metal contracts, grease stiffens, and a roller that was marginal in October can seize solid in January. If your door has been dragging for a few weeks, it's worth booking before the cold snap finishes the job for you.