BTW, it seems to happen after the engine has sat for awhile
(months) and during cold weather starts....
snip

Only an outside chance but... Have you been using a starter fluid on those
cold weather starts? They have a reputation for bending pushrods on many
deisels. Not seen it happen personally (yes, I've cheated when faced with a
no-start), but many manuals contain the warning.

Some good suggestions on care and feeding in the previous posts. Liked the
hammer diagnostic too!

surfnturf