This may sound stupid, but if i change the oil in the converter can that help diagnose if its going bad?

or do i have to remove it all and inspect the internals?

the bushings is an interesting one because the dealer made me change them saying that the vibration i was experiencing when braking was from worn out bushings hmmm i have to be pushy on that subject when i go back in...

fyi i am also out of warrenty extened too....but i think my dealer gives 2 yr warrenty on any work they do...