I have bone grips on my citybike handlebars. One of them is stuck, it has probably been on the bars for 70 years. I can't get a shim under them as they are brittle and likely to break. I'd like to avoid that as they are $60-$80 to replace. I'm hoping to get some warm soapy (Dawn) water in there to use as a lube.

Any recommendations or warnings? I am most worried about staining the bone.