The "official" repair agent for Linhof in the US is:

Martin Arndt
Marflex Service
117 Anchorage Rd.
Havelock, NC 28523
252-652-4401
Marflex@aol.com

Martin stocks Linhof parts and has the necessary equipment to calibrate the rangefinder and grind cams for lenses that don't come with them.

Call Martin before you send anything - sometimes he's backed up.