Thats years of Gookus that has collected in the machine.
You will have to tear the machine down some in order to
remove the bulk of it.
2 screws holding the front panel on at the bottom
2 screws holding the top down to the cabinet.
roll top back against wall
remove clothes guard cover (will have alot of gookus in it)
Use some type of lone brush to get between the tubs
like a refrigerator coil cleaning brush.
reassemble and run a few empty loads with bleace added to
flush out the gookus you knocked loose.
Source: Amana washer lw8252 leaving spots on clothes