-snip-
About BitcoinCore - how do I specify my old key?
Thanks!
The private key is the one starting with 5, L or K. To import it into your bitcoin core wallet click:
Help -> Debug Window -> Console once you are there you need to unlock your wallet for 120 seconds (or less) with:
walletpassphrase YourSecretPasswordHere 120Make sure you have no shoulder surfer, the password will not be masked.
Once your wallet is unlocked you have 120 seconds to import the private key with:
importprivkey 5.... The wallet will rescan the blockchain to search for transactions, even if there are none. This can take a while.