Follow the link above to heartache.
Here's the update on my status:
The gear, key, dampener all were replaced. I had tried JB Weld (alone), Loctite, welding the woodruff key in place, and a combination of these. George Fourchy has a nice writeup on crank cancer on shotimes.com
I'm going on week #2 now with the current "fix". The woodruff key was JB Welded in place, with the gear placed on, the retainer disc & dampener in place, and the crank bolt snugged. It was left a day to cure, and then the front half was disassembled & welded - crank gear to retainer disc to dampener, and then the bolt itself was welded.
This approach requires NO lower timing cover. I currently have all 3 covers removed & the CPS wiring zip-tied out of the way to keep it from rubbing on the timing belt & waterpump pulley.
The downside is (in my case) the weld on the gear side cut into the timing belt. I have about 1/8" of timing belt that's been worn away. The cutting seems to have stopped at this point, but I'm checking it daily.
There is no clacking from the gear area at this time, so (knock VERY HEAVILY ON WOOD) I may be good for a while. I only needed this car (89 SHO beater) for a couple of weeks until my 95 SHO gets picked up in Michigan.
Look for a worn / material removed area on the left side, back end of the woodruff key on the crankshaft. By the time I had messed around with it for a couple of weeks, I had gone through 4 woodruff keys, 3 timing gears, 2 dampeners and 2 retaining discs.
The RIGHT fix for this condition is to replace the crankshaft.
Best fo luck, and I hope this is not your problem.