When tearing down for a good re-build, many parts can be cleaned with a toothbrush and some brake parts cleaner. Be sure your parts are not made of ABS though since the parts cleaner will eat them. To test this, put a little on a paper towel and rub the part. If the towel turns black or the part gets sticky, do not use the parts cleaner.
Brake parts cleaner is great for cleaning your engine during a rebuild too. Just watch out for brittle plastic which can melt when exposed to brake parts cleaner.