20 - 40 minutes
My girlfriend's iPhone 5c suddenly had very low volume using the earpiece speaker. It was fine in speakerphone or using headphones, and no changes in settings were able to resolve the issue.
The reassembly process was a bit challenging. After replacement of the speaker, the problem was unchanged. Ultimately it was disassembled and reassembled about four or five times, and at one point the replacement speaker stopped working entirely. I finally replaced the original speaker and the problem was finally fixed.
I'm not exactly sure what the issue was originally. The two coil springs on the speaker and the little hook on the speaker bracket are pretty tricky to reassemble. I'm grateful for the tools and the detailed disassembly guide though, and it's working now.