Is it normal for a brand new washer to have black spots in the detergent tray?

That's likely a combination of residual manufacturing oil and standard mold spores that found a perfect breeding ground in the moisture from those initial test cycles. When these machines sit at the warehouse or factory, they sometimes have a thin film of lubricant on the plastic components. When you ran that first load and then shut the drawer for two weeks, you essentially created a petri dish. The airtight seal on those LG dispensers is surprisingly good, which is actually a downside because it traps every drop of water inside with no airflow. You need to pull the drawer completely out of the machine by pressing the release tab—usually a colored lever in the middle—and scrub the entire housing. Don't just wipe the tray; reach back into the roof of the dispenser cavity where the water jets are. If you see it coming back immediately after a wash, you're probably seeing **biological film** or undissolved detergent residue being pushed through the lines from that first sitting period. Run a dedicated tub clean cycle with a heavy-duty cleaner or a cup of bleach to flush the internal hoses that lead from the drawer to the drum.

The most important habit to start right now is leaving the dispenser drawer cracked open whenever the machine isn't running. It feels counterintuitive to have a brand-new appliance looking "unfinished" in your laundry room, but it's the only way to prevent that sludge from returning. If you keep it closed, the standing water in the siphon caps will never evaporate, and you'll be cleaning mold out of there every single month.

Also, check your detergent usage. Most people use way too much, and the excess soap builds up behind the tray, turning into a sticky paste that mold loves to eat. You really only need about two tablespoons of HE detergent. If you're seeing "black spots" reappear that quickly, it's a sign that the initial colony wasn't fully killed off or there's still moisture trapped in the upper spray assembly of the drawer housing.

I've been wrenching on these things since the days of porcelain tubs and mechanical timers. What you're seeing is what I call 'factory funk.' These units get wet-tested at the plant, then sit in a humid shipping container for months with that test water stagnant in the internal lines. The plastics they use today are nothing like the old stuff; they seem to attract slime. I've always had better luck with a heavy dose of Borax to strip that initial film off. These high-efficiency machines just don't use enough water to flush thier own guts out like the old top-loaders did.

Ugh, totally been there. My LG did the exact same thing right after install. One thing people forget is to check the actual water supply lines too. If your house sat for a bit during those renovations, you might've had some sediment or gunk break loose when you first turned the valves back on. It settles right in that tray and looks gross fast. I'd just pop the drawer out, give it a good soak in some vinegar, and make sure you're not using those thick fabric softeners. That stuff is basicly mold food.

Classic LG WM4000H series move. You prolly used the liquid detergent cup for that first load, right? Those blue siphons are notorious for holding a pool of water that just breeds slime if the air isn't moving. Since you're doing renovations, check if your contractor bumped the leveling. If that unit is tilted even slightly forward, the tray won't drain back into the drum properly, leaving a stagnant puddle in the housing. Throw a level on top of the cabinet; if it’s off, that 'sludge' will be a weekly guest regardless of how much Affresh you throw at it.

Oh wow, I had no idea about the 'factory funk' or the leveling thing. I'm totally new to front loaders, so this is all a bit overwhelming. If I start leaving the drawer open like you suggested, does the main door need to stay open too? I'm worried about my cat crawling in there if I leave everthing hanging open. Also, is the 'biological film' dangerous for my clothes, or does it just look gross? I realy don't want to ruin our new towels on the second wash!