If I recall correctly, the mounting frame of CHM's
G-15 is seriously warped,
 perhaps as the result of the machine having been dropped at some point.
  That doesn't bode well for getting the drum working.  Getting an additional
 G-15 may not just be a factor, but a requirement. 
I think the drum is shockmounted? I can not remember.
Still, a hard landing...
--
Will