How do I remove the agitator on an LG WT7405CW to get my sheet back?

That center cap is exactly where you need to start. Use a small flathead screwdriver to gently pry it up; there’s usally a tiny notch on the edge specifically for this. Once that’s off, you’re going to see a single **10mm bolt** in the center. It might have a Phillips head slot as well, but I highly reccomend using a socket wrench so you don't strip the head, especally since it might be stuck from detergent buildup. The real issue is that since the fabric is jammed underneath, it’s creating a ton of tension that makes pulling the plate straight up nearly impossible even with the bolt out. After you get that bolt removed, do not just yank on the plastic. Try to wiggle the wash plate side-to-side while applying steady upward pressure. If it’s being stubborn, you can sometimes thread some sturdy twine or zip ties thru the small holes in the wash plate to create makeshift handles. This gives you a much better grip than trying to claw at the smooth plastic with your fingernails.

Don't be surprised if the sheet has some grey or black grease marks on it once you finally get it free. That grinding noise you heard was the fabric being pinched and dragged against the metal drive shaft or the bottom of the outer tub. If the sheet is wrapped tightly around the splines of the shaft, you’ll have to be patient and unwind it slowly. Don't use a knife to cut it out unless you're absolutely sure you won't nick the rubber seal underneath, or you'll end up with a leaking machine on top of a ruined sheet.

These LG low-profile machines are notorious for this if the load isn't balanced or if a sheet happens to "burrito" other clothes. In the future, try to drop the sheets in loosely around the edges in a donut shape rather than laying them flat across the bottom. It keeps the fabric edges away from that small gap under the **impeller plate** where they like to get sucked in during the heavy agitation cycles.

I just got one of these machines and now I’m scared to do laundry. Does the zip tie trick actually work without snapping the plastic holes? I feel like I'd end up breaking the whole plate if I pulled that hard.

Also, is there some kind of mesh bag big enough for a fitted sheet to stop this from happening in the first place? I’m still figuring out the settings and usually just hit 'Normal' but maybe a gentler cycle woud keep the fabric from getting sucked down there.

Don't bother with the mesh bags for bedding. A bag that big usually ends up throwing the tub out of balance during the spin cycle, wich is a whole diffrent headache.

The 'Normal' cycle is the culprit here. It uses less water and more aggressive pulses to save energy. Switch to 'Bedding' or 'Bulky' instead. It fills the tub higher to keep the sheets buoyant and away from that gap. Also, check the splines on the underside of the wash plate once it's out. If that grinding was the motor spinning against a stuck sheet, you might have stripped the plastic teeth that grip the metal drive shaft.

If that plate won't budge after you pull the bolt, it's likely just 'scrud' and soap scum acting like glue. I usually pour some really hot water right into the center hole and let it soak for 15 minutes. It helps dissolve the gunk that's fusing the plastic to the metal shaft.

Also, check the splines once you finally get it off. If they look stripped or rounded off from the sheet getting jammed, you might actualy need a new wash plate. If the plastic teeth inside that center hole are chewed up, the machine won't agitate correctly even after you clear the jam.

One thing to watch out for once you get that plate off is the small stainless steel washer sitting on the drive shaft. It often sticks to the underside of the hub and then falls into the outer tub when you're not looking. If you lose that, the plate will sit too low and you'll get more grinding. Also, give the underside of the impeller a good scrub with an old toothbrush; that’s where the biofilm relly builds up and causes those 'musty' smells. Check the plastic splines inside the plate's center for rounding too, just in case the jam stripped them.