If you are an active member your pin is 4 digits. The first two are the month you entered the plan (started work with a participating employer). The second two are the year. For example, if you started work January, 2002, then your pin would be 0102. If you are retired, then your pin is the month & year you retired. July, 2015 the pin would be 0715.
Did you maybe try the last of SSN?
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