In the beginning, When you fuly open the two handles, jaws loosen, so you can push and insert the stem. If you can’t insert the rivet stem into the noozle.. Just push harder.

When you close the two handles, the jaws tightens around the rivet stem, biting on them. The bite may become too tight, causing the stem to get stuck inside the jaws.

“stem” = the thin, long piece that is designed to break when elongated.

“jaws” = two small metal pieces with grove (or “teeth”) on the inside surface to catch and hold the stem.

Note the spring pushing on the two handles are much weaker than the spring hidden in the barrel.

Q: does the spring in the barrel help me Close or Open the handle?
%%A: close, but am not too sure

— After you install the rivet, you need to remove the stub from the jaws. What if stuck? You can google. I think lubricating helps.

— safety

Warning: some metal pieces may fly. Therefore, you are always advised to wear glasses.