MOTM

I would agree with Paul that karma or mojo can be 99.99% explained.
To those purists who say replace all the parts with "original 
replacements" I would point out that the caps very likely have 
degraded over time and since many of the parts used were surplus the 
caps used may have already been significantly degraded by the time 
this particular unit was built.  I would replace everything with 
upgraded parts except in those cases where this changed the 
designers intent, for example if Don Buchla was relying on the 
terrible slew rate of a 741 for a particular effect then that part 
should be replaced by a 741 or similarly bad opamp.
I used to play on a Buchla quite regularly although it wasn't mine 
and it was a learning experience although I never would have bought 
one for the many reasons that have been previously mentioned.  I 
much preferred my minimoog although I eventually sold it as well.  
It sounded great but required tuning after every song.  It was one 
of the first.  The later ones were more stable but did not sound as 
good either.  
We have the best of both worlds with the MOTM which both sounds 
great and stays in tune. 
I used to rebuild synths many years ago and I would agree that no 
one in that business ever charges enough, in part because it always 
ends up taking you at least 3 times as long as you originally 
estimated and by the time you get a real handle on it you are 
committed.