Yes, it's fairly common for a timing gear to fail, but the cam usually quits turning when it does. A couple of teeth will strip on the fiber gear, and the crankshaft turns, but not the cam. Here's a quick way to check the cam timing:

Remove the valve cover, and pull the spark plugs. Watch the #6 cylinder valves. Turn the engine with the fan until the exhaust valve starts closing. Keep turning the engine over until the #6 intake valve starts to open. The #6 piston should be at top dead center on the exhaust stroke, and the #1 cylinder will be on TDC on compression, with the distributor pointed to the #1 plug wire, and the points just barely open. Any other relationship between the valves and pistons indicates a jumped/stripped timing system, either chain or gears. This works on all engines with an even number of cylinders, just use the cylinder halfway down the firing order from #1.

Inline 6: 1 5 3 6 2 4, companion cylinders that come to the top together are 1&6, 2&5, and 3&4.

V-8: 1 8 4 3 6 5 7 2, companion cylinders are 1&6, 8&5, 4&7, and 3&2. Works every time!
Jerry

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