You can resurface them yourself with emery paper. I've done this with great success before. I have a 10 year old post somehwere on here describing the procedure. here it is, just look for the third reply by norm.
http://www.zcar.com/70-83_tech_discussion_forum/cam_questions_595162.msg901388.html#msg901388
http://www.zcar.com/70-83_tech_discussion_forum/cam_questions_595162.msg901388.html#msg901388