This indicates a broken seal. Replacing it is not that bad IF you can get it apart, but you need a special tool to do so. This tool is not something you can pick up at a hardware store. This is old and it would not be uncommon for the parts that need to be removed to be seized together. I would move on here and buy a new washer-you have gotten your use out of it and just replacing one part does not give new life to any other.
The washer does not leak as much when doing a med load , is that still the seal