Android Phone Stops Syncing Contacts to Gmail

My Android phone stopped automatically syncing my contacts with Gmail.  Even if I went through the Settings menu and chose to do a manual sync, it would go through the motions but wouldn't update my contacts, and I also noticed that the date/time of the last sync wouldn't change.

I finally found the answer.  Many thanks to the user Peaser on this website:
http://androidforums.com/eris-support-troubleshooting/81579-fix-google-contacts-not-syncing.html

The solution:

In your phone, go to Settings, Applications, Manage Applications, and under the All tab, choose Contacts Storage.  Then push the "Clear Data" button.

Then resync your phone to Gmail:

In your phone, go to Settings, Accounts & Sync.  Under Managed Accounts, choose Google, and press the "Sync Now" button.

Followup (3/2/2012) 
I wanted to share a followup to this story.  A few days later I noticed my contacts weren't syncing again.  The behavior was slightly different.  Previously the date/time on the last sync didn't change.  This time it would update the date/time of the last sync but wouldn't actually sync the differences between my phone and Gmail.

So, I did this:

• Settings
• Accounts & Sync
• Select your Google account
• Uncheck "Sync Contacts"

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• Settings
• Applications
• Manage Applications
• All (The All Applications Tab)
• Select Contact Storage (I'm told that on some phones it is listed as "Google Contacts Sync")
• Press the Clear Data button (which purges all contacts from your phone)

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• Settings
• Accounts & Sync
• Select your Google account
• Check "Sync Contacts" (which should cause it to re-download your contacts from Gmail)