MK1 sound board too hot - common problem?

[Arcade-Projects]

Hey there, looking for some insight -- a friend of mine has an MK1 pcb, but he complains the sound board runs way too hot.

Game works fine, sound is fine (no garbage, pops, anything), but the amp gets so hot you can't even touch the heatsink.

Is this a common issue? What could be causing this, some sort of short? Bad amp IC? Failed thermal paste/adhesive between the amp and heatsink?

I'll take a look into this later this week, it'd be nice to know beforehand if anyone has witnessed this problem.

Thanks!

More...