Ben Jackson wrote:

My S-Tec 50 needs adjustment (chasing the heading bug) and I'd like to
find a shop that has the S-Tec autopilots figured out.

Any recommendations in the Pacific northwest, preferably close to the
Portland/Hillsboro area?

At Aurora, Pacific Coast Avionics has a good reputation. Unfortunately,
when I was there they were so popular that I couldn't get them to focus on
my airplane because they were too busy. I ended up getting some avionics
work done at PDX Flightcraft instead.

More recently, I was impressed by the avionics showroom at Hillsboro
Aviation, and even more impressed with the responsiveness of their
maintenance staff to a couple issues I had while there as a transient.

Those are three options for you to investigate.