We cover Linn from Jefferson City, about 19 miles out. That distance doesn't change the work once we're on site - a roller swap is a roller swap - but it does mean we schedule it as a dedicated trip rather than a drop-in, so it helps to describe what you're hearing (grinding, binding, door catching on one side) when you call so we bring the right roller stock the first time.
On site, pulling and replacing a full set of rollers on a double door, including the hinges if they're worn the same way, is most of the job - track alignment check included, since a bent rail will chew through new rollers just as fast as it did the old ones. The honest limit here: if we get the door open and find the springs are also original and fatigued, we'll say so before we close anything up, because sending a tech back out from Jefferson City for a second trip costs you more than doing both jobs in one visit would have.