32 character starting with 917b
There's this:
Private Key in uncompressed Hexadecimal Format is 32 bytes, or 64 characters in the range 0-9 or A-F.
If the characters are all 0-9 and A-F, it's hexadecimal. If that's the case: could it be you're holding half the key?
If I enter 917b917b917b917b917b917b917b917b917b917b917b917b917b917b917b917b in
Bitaddress.org's Wallet Details tab, it produces a valid private key. But that's 64 characters.