i think these jaws are precious gems. listings i've seen list them as sapphire even tho they are not blue. i dunno but i wouldn't want to chip them when i have 25 other ways to compress a springThat spring looks no bigger than 5/8-inch in diameter.
Do what tourmax said. Compress the spring. Then, wrap a thin baling wire to hold the compressed spring. Place on the shaft. Put on the C-clip. Cut the baling wire.


