Failing lower ball joints?

[Ben Fenner]

What are the symptoms (noises?) of a failing front lower ball joint?
I think mine are way past failed, but I'm not sure.
I hear a pronounced thumping sound everytime I accelerate from a stop.
I feel like when I stop, I re-seat the ball joint, and then when I
accelerate, I pop it loose again. I'm going to fix an engine mount
problem I have, and then see if it continues. But, does anyone know for
sure what happens when a front lower ball joint is failing? Aside from
sudden death.

-Ben Fenner