Stay away from the decals, but a good solution of OxiClean and Hot water does it for me. Then a good wipe / rinse with hot water to clear the Oxi away.
It's possible the oxi wouldn't have taken the decal off my 127, but the OxiClean and a microfiber cloth did. I noticed quickly, it's about 3/8" sq, but still. The underbits should be totally fine as long as they're well oiled afterward. I always use the air compressor to blow out as much water as possible, then oil immediately afterward.