The Lab5's are worked on with a 'suitcase'
I think the dealer/repair shop will order every part needed. .then you get to pay for what is needed. I had to have an amp module replaced in one of mine. It malfunctioned above volume level 42.
The buzzing might be something to do with the amp? Also, never hurts to try a new chord?
Thanks
MJM
I'm ready for something new that I actually want to buy!