The model number doesn't make a match at RepairClinic.com, and I'm not sure if this is mid 1980s belt drive or a more recent direct drive machine.
If it's direct-drive (there's no access panel on the back), there's not much to the drain process. The pump attaches directly to one end of the motor, driven directly by the motor shaft. The motor is reversible for agitate and spin/drain. When it runs in the agitate direction, the pump forces water back into the tub rather than draining it out. In the spin/drain direction, it drains. Or should. The pump apparently isn't frozen-up or the motor couldn't run at all. Perhaps the tub outlet is blocked by a stray sock or other small article that got out of the wash basket?
If it's a belt-drive machine, then the pump could be frozen and the machine will still run, but under a load and not for long before the belt would/should start burning. Another possibility is that the flapper valve arm isn't properly engaged in the agitate shift bar, the flapper valve is broken and stuck in recirculate mode, or the impeller is loose from the pulley shaft.