Well, it happened. It started with a soft ticking, which turned into a definite clicking. I knew something was up, so decided to turn into a shopping mall driveway to check it out. By the time I found a parking space, the clicking was now a clacking. I shut it off, opened the hood, and asked my husband to fire up the engine while I listened. The engine now clanking and sounding like it was missing a cylinder, so I said shut it off, and called AAA to tow it home (I was on the way to pick up some meds at pharmacy, so not too far away). I called my buddy John The SHO guy, and had him talk me through what to do next. It took a few weeks for me to gather up the courage to open up the valve cover, and this is the carnage I saw. It appears that the shim sitting in the bucket disintegrated. It may have been an occlusion or fracture that eventually led to the shim bifurcating in half and the cam rubbing the pieces against the camshaft tower support that broke one half into shrapnel, and possibly caused shavings to become deposited on the inside of the valve cover. In a couple of weeks I'll have the SHO towed to John The SHO guy's place and he'll try to assess the damage, replace the shims and hopefully get her back on the road. While we are in there, I think I'll replace the plastic "Y" connector that distributes the coolant between both heads in the valley of the V. Wish us luck.