I've never seen this, though I do try to get the part fully submerged. What kind of cleaning solution did you use?Be careful with this. I had a small ultrasonic that I used to clean a stainless steel pistol slide. I couldn’t get the whole slide in at one time. I can now see a faint line where the liquid level crossed the slide in both directions. Oil covers it up, but it is there when the oil is rubbed off.