I stopped at a shop during a road trip to acquire a Singer with Wings decals. The owner was pulling into the parking lot and saw the treadle in the back of my car. She advised wiping the machine down with ammonia on a rag to clean it, and if I see the decals silvering I've gone too far. I gently said I'd be gently cleaning the head with sewing machine oil so I wouldn't risk ruining the decals. I'm so thankful for all the good information posted on this site- people are very generous here! Turns out the treadle was in a tarp car hut. It is not in quite as good condition as expected so I plan to be Very careful. I plan to try Glenn's tutorial this summer on a practice head before I work on a good machine. It's nice to know there is so much that can be done inexpensively to restore these machines.