Last year I made sauerkraut according to directions in a Kerr Canning Book. It was placed in a warm sun porch to ferment. I used a plate with a weight on top to keep the kraut under the brine. In 2 weeks it was beautiful and tasted good.
Thinking I needed to let it go longer, I let it continue fermenting. It got moldy quickly and smelled like yeast. I disposed of it. I don't remember how I washed it out, but it continued to have mold growing inside the crock.
How do I clean the crock to keep from having the spores grow mold/yeast in a new batch of kraut? I've read about people heating crocks in the oven. This would not be possible.
I would suggest filling the crock with warm water and adding a cup of chlorine bleach and let it stand for about an hour. Then drain and rinse with clean water. Then I would set it out in the hot afternoon sun for several hours. This should kill the mold spores that might still be in the crock.
You could also line the crock with food grade plastic bag which you could get at a restaurant supply store. If you continue to have problems then you might consider making your kraut in gallon glass jars. 5 lbs. of cabbage fits nicely in a gallon jar.
One more suggestion is that you do not use your old Kerr book for food preservation information. It is always important to use up-to-date information when canning and processing foods.
Go to the OSU Extension website and you can download up-to-date information. Pickling vegetables has the latest sauerkraut making information.