You are likely to get a different answer from everyone who reads this. It can really depend on the machine itself. I never use water based cleaners on my machines but other people do. I use a soft cloth like an old diaper to gently wipe all the loose dirt and crud off. If it's still really dirty I might go over it next with a slightly damp paper towel then if it's a black machine with decals I'll gently pat it dry. After that I get a big bag of cotton balls and a can of TR-3 Resin Glaze and follow these instructions-
http://www.mckennalinn.com/cleaning-...-machines.html
Cari