AB 984246 8821 Allen Bradley
If you carefully dismantle then pot and use electrical contact spray you may be able to get an unloaded R measurement as a percentage or the max outer lead R ratio.

From page 192 on the linked data-sheet, kindly commented by @Charlescowie, you can see which curve fits the result of your $5 DMM reading.

If you are really good, you can dismantle the Pot and restore it to like new performance with rubbing alcohol and very light fine abrasives. Then reassemble all the moving parts to exact position and reconnect.