So today, I noticed it was much tougher than normal to open the trunk, like the trunk like was very heavy. Likewise, when I went to close it, it slammed shut on its own.

I assume this means that one or more of the little gas pistons that look like shocks on the trunk lid hinges have failed.

When I looked closely, it looks like one of the pistons leaked its fluid a bit.

So, can someone point me to a write-up on replacing these? It looks like there's probably a simple trick to it.

Also, is the dealer pretty much the only place to get replacements?