Hi!
Could be the actual speaker, the headphone jack OR a fuse.
Here is the fuse replaced: Loss of audio Output From Units speakers..
You need to open the console and do a continuity test for the fuse. If the fuse is okay, then replace the speaker and the headphone jack. Both are like $1 or $2.
Guide for removing the motherboard: PSP Go Logic Board Replacement
Please let us know how it goes!
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