I brought an Ansco Speedex, cousin to an isolette, back to life with a week long application of napthta to the focusing helical after taking alluminum scale covering off.
One or two drops of naptha per night from a small medicine dropper.
At the end of the week, gripped the supposed to move part with a curved jaw slip joint pliers sized to fit best.
Made a gentle but insistent tug, while trying not to squeeze the grip too tight.
After it budged I pulled the helical out of the body track, and used the head of a pin to chace the last of the damned green goo out of the assembly.
A tiny bit of moly white grease was then smeared across all three thread paths, and the front element reassembled
On to re-collimate the lens focussing scale with the temporary mylar 'ground glass' one night.
Done by looking at a distant streetlight down the road as a stand in for infinity on an otherwise moonless night.