Throttle stuck wide open...solved

Back on Sept 19 I started a thread about my bike's wanting to go to full throttle when it should have been closed. I spent a month of what days were warm enough with tank and airbox off, intakes removed, digging around throttle linkages, sliders, butterflies, cables, etc trying to solve this issue. I had many great suggestions from this group and I followed them all.
I apologize for the long silence, but I finally gave up and trailored the fat lady to Gary at GAC Ent; THE western Canadian guru for Gold Wings, especially GL 1000 to 1500. After removing the tank and airbox (again) it took him a half hour to find the problem.
Two winters ago I upgraded to Polk Audio DB501 speakers in the faring and trunk pods. After the installation the spring before last I was missing a screw for the right side speaker pod on the faring. I remember it pingpingpinging down to the engine top, couldn't find it after hours of searching with flashlights and magnetic pickups, and finally gave up thinking that I can live without it and I'll get one next time I'm at the dealer; then conveniently put it out of my mind.
Well, after over 15K miles including two 5K vacation trips to Ontario and back, this Sept that screw decided to bury itself behind and under the throttle cable barrel atop the carb bank stopping the throttle from completely closing when the grip was released.
If you drop a small part, don't stop looking until you find it. Consequences later on can be devastating.
Thanks to all of you that tried to help.
Fred.