I wouldn't be one bit surprised if the problem is due to the use of lead-free
solder in manufacture.

Do use solder using lead for the repair. It's far more reliable.

I'll keep that in mind, thanks.

The 4 attachment points for both jacks are very thin. The guy that did
the repair job in the link that I provided added quite a bit more
solder as was already there. I emailed him last night and he said that
his player is still working today (at least 2 years later). He said he
did not add any epoxy, just solder. I think I will add some epoxy
around the edges of the jack housings when I'm done adding solder,
just to add some extra strength and make sure this never happens again.