Is that the result of water ingress and the resulting rust?
Maybe it can be cleaned up using cleaning swabs and distilled water or a mild detergent. Since you are apparently planning to deep six the dial anyway it is certainly worth a shot.
Probably can't be cleaned to a level of perfection but maybe to the point of being presentable is possible.
Look for something like this: https://www.cousinsuk.com/product/co...bs?code=S35526
They also make a cleaning pen: https://www.cousinsuk.com/product/gl...bergeon-swiss#