PROBLEM SOLVED!
Since I didn't have the right sized C-clamp or socket, I improvised with the drill bit extender and hammer as shown:
1. I completely unsoldered all wires from the top plate assembly, unscrewed the new diode from its place on the rectifier plate, and separated the top plate assembly from the rest of the 1033.
2. I sand papered the contacts imbedded around the switch shaft until they shined
3. Using a small long nosed pliers I increased the bend pressure of the contact arms around the shaft
4. I inverted the top plate and secured the shaft to a vise.
5. With the shaft thus secured, I used a drill bit extender and a hammer to tap the retaining sleeve more deeply onto the bottom stem of the shaft. This cured the "wiggle" and loose contact problems.
6. I wicked away all old solder from every contact.
7. I reattached the whistle diode to the rectifier plate before soldering the diode wire.
8. I resoldered all wires back to their original contact points, reset the slot tabs through the 4 slots in the fibre plate and seated the plate, resecured the Transformer cover, reattached the binding post nuts, and reattached the red and black handles.
Then I bench tested the transformer. I checked all voltages with a multimeter, and all readings were nominal. Then I placed a whistle tender on test track and turned the now snug whistle control lever. The whistle sang loud and clear with no hesitation or linger. I replaced the tender with a locomotive on the test track and opened the throttle. Perfect motor operation resulted.
It was the long way around, but there are no shortcuts with 1033 transformers. They are elegant, simple machines.
