100K potentiometer reading 26K at lowest seting
A potentiometer is effectively a strip of carbon (in a semicircle) across which a contact (wiper) is moved. It may be that the wiper is not properly traveling to the the limits of the strip, or the strip is misaligned (rotated incorrectly) in the housing. It may also be that the strip was manufactured improperly, with a higher resistance in one area than intended.

You might be able to open it and correct a misalignment, but anything else is probably not easily possible. Depending on the cost of the potentiometer, you may be best served by simply replacing it.