A lot of washers (our front loader included) have a trap inline in the drain hose inside the machine. It manages to catch things like a bra strap that somehow got torn off a bra, broke a credit card in half and trapped it and obscene amounts of lint.
When it gets clogged, the front loader we have stops draining (possibly stops agitating too. It's been a while since we had trouble with it.). When it was on warranty, the repair man came out and removed the trap and said we wouldn't have trouble with it again because everything would just wash down the drain.
Well, I'd rather clean the trap than call a plumber (or fix the plumbing myself) so while he was here, I was watching carefully what he'd done and put it back together shortly afterward (after cleaning it out of course). Now it's regular maintenance and if we've forgotten to do the maintenance and the machine stops draining, we know where to look first. Also if I'm missing something that might have been laundered, I know where to look now too!
I did find an exploded diagram of our machine online, for the purposes of ordering parts and that shows where the trap is. This should be possible for most machines. Hopefully, it can save a few people a large washer repair bill.