L.O.
Two Questions. First, do you use HE detergents? If you don't, and use standard soaps, they leave buildup. I used to work at a prominent B&B, and once got the wrong soap for the machine, and got spots from it, as a buildup of the soap developed. This is what the Maytag guy said to my boss, and I'm not sure of the validity of this. He used some expensive product to remove buildup, and told us to use the method I listed below once every two weeks to prevent this issue. The guy was real nice, and saved us a ton from unnecessary service calls(so we always called him first when we really needed assistance).
Perhaps there is some buildup in your machine? I used to have fabric softener spotting, and I suspect a buildup of hard water deposits in my Maytag(other people used the fabric softener dispenser, and never poured water in after the softener. I only use a Downy Ball.).
What I did to fix this, is I got a bucket of very hot water, and poured it through the softener dispenser. Next, I made a Hot/Hot load on Medium, and put in a cup of Bleach and dye free soap for that sized load. After running this, I ran a plain Hot/Hot load on Medium, and put in two cups of cider vinegar.
I repeat this process every other month, or if I see a return of spotting.
The second question has to do with hard water(you never mentioned what colour the spotting is). I do, and thought of what I do for that issue.
If you do, run CLR according to instructions in your machine to remove the buildup, then a HOT/HOT load to flush the product out.
Hope this helps.