On Friday I came to send these coins back to an exchange and find that hitting the send or preview buttons did not do anything i.e. no response other than to change colour. So I seem unable to send anything from this wallet.
If you are attempting to send the whole balance, it may be that you can't due to not having enough funds to then pay the fee as well (Electrum adds the fee on, it doesn't subtract it)... What happens if you click the "max" button?
Is this a standard, MultiSig or 2FA wallet? It should say in the title bar... something like: "Electrum 2.9.0 - wallet_Name [standard]" or "Electrum 2.9.0 - wallet_name [2fa]".
Also, if you goto "Wallet -> Seed", does Electrum ask for your password and then show the seed?