MacBook Speakers sporadically not working?

My 2008-model Aluminum MacBook (13", if that helps) is having some major trouble with the internal speakers.

Over the past several days (with similar problems happening about a year ago), they stopped working sporadically for periods as little as a few seconds and as much as a few minutes; sometimes fine for day, other times happening every few minutes for a few hours. Just before they stop working, I will hear three soft but audible pops (or several sets of three if it's really bad), the volume on the toolbar grays out, which is also the same when I look in settings.

At the moment, they haven't been working for about 20 minutes (although I just heard some pops, so maybe something will happen soon)

Headphones seem to work fine, and no issue with the microphone either.

What could this be? Is there a quick, or at least a DIY, fix? I don't really have the money to get it repaired, so I will have to live with earphones for a few months.

Thank you!!!