Recently cleaned out the lower spray arm ports and there was crap in there. Made a difference IMHO. Upon inspection realize that top rack items clean poorly.

Wife says after 12 years we need a new dishwasher. I would agree, except we need other things first. Living in MI we have excellent water and few problems with mineral deposits, but nonetheless it happens. After this long, there have to be areas that require attention.

I pulled up a schematic but it shows only parts. I'm thinking I need to access the upper spray arm to clean out the ports and also check water supply.

Should I run 'tang' or CLR through it?

In another post someone else had a similar problem and asked about using CLR. Ever try it?

Is it easy enough to remove the upper arm that I can disassemble and see where it's plugged?