The attachment is so easy to attach, use, and clean!!!!
I usually see what's on sale, and that's what I grind. Trim off any excess fat you don't want as well as gristle, and NEVER grind bone. Also where the meat comes together a lot of times there is a thin layer of membrane, it's best to remove that as much as possible, it will get wrapped around your cutting blade and make it more difficult for the meat to pass through the grinder plate, and you need to stop and clean it off of the blade more often.
I like to cut my steak or roasts into strips. About 1 1/2 to 2" wide strips, doesn't really matter how long. By doing this you can literally "feed" it into the grinder and rarely have to use the "poker". The directions say to grind on speed 4-6, I find the faster the better.
I grind chili meat using one of the bigger grinder plates. Below is a site I found to order different size grinder plates.
It is suggested to use a larger grinder plate, then put the meat back through using a smaller one, but I don't find that especially necessary.
There is nothing that matches the flavor of fresh ground burgers.
This site sells grinder blades and replacement parts for older KA stand mixers as well. I've ordered grinder plates from this site. You may be able to find them cheaper on others sites, but I have not purchased from any other site, so I can not recommend them.
NOTE: If grinding a lot of meat, it might be wise to stop about half way through and clean around the blade. While your grinding, if you start hearing the meat do a kind of snap, crackle pop sound, it means there is gristle or membrane around the blade and it is struggling to grind the meat. So it's definitely time to clean it. FYI, turn your KA sideways or away from you while grinding, it keeps from "spitting" meat juices on you while your grinding.