Hi AUSMHLY and LAW75,
I want to thank both of you for your responses, help and encouragement. I am late responding because I spent a good part of the day laying on my back and playing with the passenger side regulator mechanism. It was time well spent and I was able to play with a flashlight also. My six-year old grandson thought that was cool too. He is being "groomed" early on as the future custodian for our Healey.
The mechanism is starting to make sense after watching the main arm move back and forward in the regulator to channel bracket when working the mechanism. And, you can see the flex in the main arm and gear as the glass moves up and down in the channel. I think everyone agrees the passenger side regulator has been stress by working it when it needed to be cleaned and re-lubricated; and it should be replaced.
I said the mechanism was "restored" previously because everyone on the Forum says that when they clean parts and have them re-plated. You are correct, none of the worn parts were replaced ten years ago and none of its working clearances were changed. So, I have ordered a new passenger side regulator.
Arm movement within the regulator to channel bracket is very interesting as the arm moves back and forth. I will replace this part also if the newer ones are any longer. Being a little longer would allow the arm to increase lift slightly. I can see how both the regulator and the amount of lift can be optimized for a given set of parts. As of now, I can also tune the movement and lift a small amount by also carefully repositioning the bracket on the bottom channel.
OK, moving the stop bar to its limit and better lubrication within the regulator to channel bracket provided another half inch of lift at the rear of the glass where it was needed. The new regulator should remove any flexing. I am documenting my observations and ideas for the young custodian. He might forget our discussions 50 years from now when he needs to review the information again.
The less you understand a mechanism, the more words, details and pictures help. But, you guys were absolutely correct: "Sorry if I'm not being detailed enough. Sometimes it's best to fiddle around with what someone is trying to explain. The stop bracket is held in place by two screws or bolts. Loosen those move the bracket, tighten them up. It'll be evident where to position the bracket after you roll the window up".
Those instructions made all the difference!
Pictures after adjustment.
Thanks again.
Regards, Bill