I believe you might have a pre-bip39 wallet seed.
This link might be helpful
https://blockchaingetback.com/posts/how-to-recover-blockchain-legacy-mnemonics.html
I had a similar situation and successfully restored my wallet .
Blockchain can also assist you for a 10% fee (as I understand it) if you are unsuccessful on your own.
Remember, you should be able to recreate the (custodial?) wallet using only the seed, password not needed.
But it will never work in electrum because you (most likely) have a custodial wallet and not a “full” wallet.

Good luck