Rollers on the bottom two panels are low-risk DIY - no spring tension involved, just a hinge pin and a stem. The top rollers, the ones riding near the curved section of track by the horizontal rails, are a different story: a slip there while the door's heavy with age can put a roller through your hand or drop the section on your fingers. If your Keller house still has its original 1999 opener too, swapping rollers is also a good moment to have someone check the opener's force settings, since a quarter-century of use loosens most factory settings.
Our honest line: if more than half the rollers on a door are steel and seized, replacing just the noisy ones is a short-term patch - the rest will follow within a year or two, so doing the full set at once usually costs less than two separate truck calls from Bedford.