I am not an expert in repairing it, but I have read up on specific details regarding what makes the squeal. It isn't dried lubricant. It's more akin to a pin that rotates in a hole, and through forces acting upon that pin the hold elongates to an oval shape and the pin starts wearing oddly as well.
All those "fixes" to quiet the noise with drops of oil strategically placed are only band-aids on a larger issue.
The issue would be addressed by a proper CLA. If you got a CLA and it didn't resolve it -- you got ripped off. They didn't do a full cleaning and didn't replace the worn parts. I had an AE-1P that squealed horribly for many years until I got it CLAed. When it came back it was quiet as a new model and it has remained so for many years and to this day.
I'm sorry to say I think you got swindled for the most part on your past CLA experiences.
H'mm so what about all the A model Canons that haven't been used much to wear anything out, but have the squeak................