When the hardware's original and the panel's sound, we replace rollers, re-square the track, and rebalance the door against the actual panel weight rather than whatever the spring happens to be doing now. If the spring's near the end of its rated cycle count given the age of the house, we replace it at the same visit rather than leave you with a second call in six months.
When the call is for full replacement - bowed panel, opener that's failed outright, or a homeowner wanting the insulated upgrade that higher-efficiency homes in this area often go for - we size the new door and opener to the opening as it exists, not to a generic standard, and we test the balance by hand before the opener ever gets reconnected. See our coverage for Tellico Village or the full installation page for Maryville for what this looks like outside a straight swap.