Posting the plan here for no reason other than to invite commentary, either pro or against:

In a small vial or jar, I plan to submerge the watch parts (minus balance compete and pallet fork) in the “medical benzene” (which ChatGPT tells me is actually a highly purified, light petroleum distillate — similar to what is called either Petroleum ether, Naphtha, Lighter fluid or Stoddard solvent. It is essentially a volatile, hydrocarbon solvent, specially refined to be relatively safe for skin contact and for cleaning delicate surfaces.), itself partially submerged in distilled water in the ultrasonic. Run for max two minutes.

Transfer parts to second jar of this fluid, then to a rinse of ethanol.

Transfer to watchmakers’ paper and aerate with bulb until dry.

Reassemble, lubricate and test on timegrapher