Washer makes holes in clothes and i want to replace the tub.

i have a kenmore 80 series washing machine. For some reason when i wash clothes, it makes tiny holes in some of the clothes, but not all of them. Usually new ones or favorites. I can find no other way the clothes are getting holes in them. I have checked for rough places in the enamel but can't fined anything. I got it from my aunt who had replaced the tub once before for similar problems, but she said a pair of overalls with buckels chipped it before. She had an extra tub, now I want to replace it even though I can't find anything wrong. I have taken the plastic agitator off but can't figure out how to get a metal piece off so I replace the tub.