The most common fault, I found with my experiments, was overloading the washing machine. Naturally, clothes cannot swish around, if there are too many of them in the washer. You may have a ten pound capacity washer (some machines have only eight pounds) but you probably have no way to weigh the clothes. The way to test this is to fill your washing machine with water first (on top loaders) and then put your clothes in.
After the agitator starts, look in the machine to see if your clothes are swishing around and turning freely. If your clothes do not change position immediately, you have overloaded your machine and your clothes will never get really clean. Take some clothes out. Eventually, you will be able to judge without going through this procedure.
~ 1962 Heloise’s Housekeeping Hints