Rejuvenating wringer rolls...
First off, Carolyn - welcome to the website! Hopefully you will find this club as useful and fun as I have!
If the cracks are only surface ones with some rough spots, you could probably lightly sand the rolls by hand. I stand a roll on its end and maintain the curve of the sandpaper to the roll as I do the sanding.
Depending upon the depth of the cracks, you may want to consider an electric belt sander, but caution is required so as not to remove too much material - and also it must be done uniformly (of course.) For the Model 90, I used a stationary belt sander and slowly and evenly rotated the roll. You definitely don't want to take off too much material on Maytag rolls, as reducing the diameter will affect the pressure when applied (as there is no way to increase pressure on a Maytag.)
Another method of repair that I've done with some success is by using an RTV rubber/silicone to fill in the cracks. Black "PERMATEX" silicone is good for the upper black roll in a Maytag. You could use a clear equivalent for the beige rolls on other machines. I've also used E6000 adhesive for this purpose.
Hope that helps! Best of success!
-Brad