Recommendations for reliable service of Audio Research or tube gear near Wisconsin?

The Ref 3 should be fine for many, many more years to come. I wouldn’t worry about it especially since you’re not too far from them if you wanted to make the trip and shipping probably not too bad. Not to discredit a quality tech, but a preamp to that caliber I would send it back to ARC regardless and not take a chance on it. Have the tubes checked if you can, and when the time comes, spend the little extra and buy new tubes from ARC or make sure it’s a trusted seller if you go elsewhere.

i agree w adg101 100% - a ref3 should go back to arc to work on

op you are in wisconsin, not santiago chile

ARC gear is very serviceable, either at ARC or any competent tech. ARC has also always made schematics readily available - in the old days, the full schematic was included in the back of the user manual.

The shop I mentioned is in Rockford, Il. 
 Not sure if your close or far, but I made the drive one weekend, and came back in 2 weeks.

  We are about 3 hours away. Worth the drive, plus much safer than shipping, I will never ship electronics again. 
  Dreading the Cali road trip if something ever goes wrong with my amps.  

Thanks for the help. Sorry for late reply