I picked up Raptar lens set in a Rapax shutter. The shutter fired, but was slow. There was a bit of crude on the outside that presaged the state of the works. I put it in the tin that I use for soaking shutters. Given the amount of dirt, it didn't seem that just letting it sit would be adequate. As the tin has a lid, you can swirl it around. After doing that for a couple minutes, I just wasn't feeling it.
I had often thought of getting an ultrasonic cleaner, but never did it. Then it occurred to me. I have a ...device...that vibrates. It wasn't immediately clear how this could be used. The ...device... is of a rather unique shape and was intended to interface with something very different from a lens soaking tin. But with a gum band and some bottles to brace it all, the tin was securely attached on top of the ...device. I left it run for about 30 minutes. I didn't want to use up all the batteries, in case I wanted to use the ...device... later.
It worked great. The shutter came out looking and working like new. No, I am not going to post a picture.