When I was getting "sud" repeatedly on my HE3, I cleaned the drain pump filter and it was the abvious problem when I found what was in there. Takes about 10-minutes.
1. Take off the lower front pannel (3-allen socket screws across the very bottom)
2. Turn the large round pump filter cover disk counter-clockwise by hand and remove. Be prepared to catch any water draining out.
3. With a set of needle-nose pliers, pull *straight-out* the disc behind the cover. This is a corse filter that traps large articles (like very small socks) before the drain pump. Don't ask me how they got there, but there was three of them. Clean, re-align and insert filter.
4. Replace the filter cover and lower panel.