Last year I let a young neighbor borrow my washer and dryer to wash her young son’s clothes. When I did my laundry the washer would not expel the water. I set it aside and installed a new Samsung HE top loading washer. When I got some help from my yard man, I took the old washer out and poured the water out. An examination of it revealed a child’s sock locking up the water discharge pump. I set the Samsung in the back of the laundry room and put the old washer back. It is still working and I hope it last another 23 years.
I ordered some mesh bags https://www.amazon.com/OEXEO-Laundry-Mesh-Bags-6PCS/dp/B06XB63727/ref=lp_15962593011_1_6?srs=15962593011&ie=UTF8&qid=1522900718&sr=8-6 and my ask my neighbor to place all small items in one or more to wash.
If they get to the pump you will probably y have to take the hose to the pump off to retrieve it. The most frustrating thing is an object like a quarter that gets to the drain hose and intermittently blocks the water like a ball valve depending on its position in the hose, horizontal or vertical.then there are small objects such as broken plastic or bra wires that come loose from frayed bras-that possibly can make it to the trap in the house drain, they act as a dam and lint slowly builds up behind them until the trap is blocked and you will need a flexible pipe cleaner/auger to get the rats nest of lint etc out of the trap.
the mesh bag and checking pockets for objects and bras for fraying and not overloading on high water level setting is the best prevention.