Good news and bad news. Following Dan Daniel's good suggestion, I was able to remove the middle group safely. But in the process of removing the synchro part, I broke some parts. So the project is on hold until I find another 800 shutter.
As Dr. Dan Daniel prescribed, I bought supplies from Home Depot.
Cut a strip of gasket, and pick the clamps of right size:
Tighten but not over-tight, use the gloves to grab and use your muscle. It came off nicely after two tries. Remember to mark where the two part separate since there are multiple threading positions.