Compression Loss -- Cause

[shawn]

I was thinking about the possible causes of lower compression readings in a
cylinder and came up with the following.  I will list from what I guess to
be the most to least common.  I would love to know what other causes there
might be or what changes should be made to the order.

1. Worn Rings
2. Worn Valve guides
3. Worn Cylinder Walls
4. Worn Valves
5. Leaking Head gasket
6. Worn Valve Seats
7. Cracked Head
8. Cracked Block