Call or send an Email to Dennis Bushnell down in Auburn, Washington (just a little south of Seattle):
Phone: 253-826-2233
E-mail:
bushcycles@aol.com
I have known Dennis since '98 and have no qualms about recommending his services and tandems.
You can read a little bit about Dennis here, but it is in no way representative of his breadth and depth of experience:
http://www.sandsmachine.com/bp_bushn.htm