I don't think there are any yearly maintenance requirements, but here is what I would suggest.

1. Use only HE detergent and use as little as possible. This is very important.
2. Unless you are really wedded to the idea of fabric softener, forget it.
3. Clean out the drain pipe and collection area regularly.
4. Do not overload the machine. An extra wash every now and then is a lot less expensive than a repair.
5. Keep the machine clean and in as dust free area as possible. Electronic controls hate dust, heat and moisture.

Goo luck, hope this helps.