Synchro-Compur shutters: I avoid them like the plague, I did exactly what you described, I opened one up and tried to clean it. I would have been better to go out and dissemble the transmission on my truck to clean and adjust it. If there is a line that has to be crossed it's the Synchro-Compur shutter that is on the line.
Anyone want or need a bag of Synchro-Compur shutter parts? I kept it as a cautionary tale of what can happen when a person gets in over his/her head.
Thanks for posting this for all to see.