Is it normal for rust to build up under the agitator on a Whirlpool washer?

I've had a Whirlpool top loader apart a couple times and that brown crust around the agitator base is almost always fabric softener residue mixed with lint and detergent. Softener is wax-based, it sticks to everything below the water line and builds up in layers. Scrape what you can with a plastic scraper, then run a couple hot cycles with washing machine cleaner or a good glug of white vinegar and it softens the rest enough to wipe off. The stuff bonded around the base will take a second pass but it does come off. And honestly, if you use liquid softener at all, that's where most of it came from. Dropping it makes a huge difference in how fast that stuff comes back.

That brown stuff around the shaft used to scare me too on my old Maytag, took it apart expecting the worst and it was just years of softener gone hard. The metal under there gets stained and it looks like rust but scrubs off with a scouring pad. As for pulling the agitator, on the older ones it just lifts off, but some have a bolt hiding under the cap, so check before you yank. If it fights you, a strip of rope under the fins gives you something to pull on evenly. Worked on mine back in the day.

I pull two or three of these a week at the shop and real rust on the shaft is rare. What looks like rust is usually stained mineral scale, and it polishes off with a bit of Bar Keepers Friend on a rag. The shaft sits above the water line on most of these, so corrosion there doesn't mean a seal is leaking. If you do want it off, warm water poured over the base loosens the gunk that's gluing it down and it lifts easier. Check the bottom of the agitator once it's off, that's where the crust hides thickest.

Update: the Bar Keepers Friend trick worked, the shaft polished up fine so that was just stained scale, not rust like I feared. But the crust around the base of the agitator is still stubborn. I got some off but there's more wedged under the bottom edge. Do I acutally need to pull the agitator to get at it, or is there a way to work it loose from above?