I just struggled through this exact situation with TIAA, who claims not to know what was deposited in the account. Finally I found that I could request a "transcript" for all account activities for the last 20 years. It was only about 30 pages and took a month to get, but it was fairly easy to scan through and look for the contributions. It may help to know that deposits were limited to $500 unil the early 2000s when the limit changed to 2,000.
