I have an old MultiBit Classic wallet, where I have received some BTC to two addresses (same wallet). When I import the private key from MultiBit (seems it's the compressed variant) to Electrum desktop, Electrum imports it correctly, but shows only transactions and balance from the first address. Transactions received by the second address (which happened years later) are not shown and I can't import the second address into Electrum, because the wallet is non-deterministic.
I would like to simply send all the money from MultiBit to a new Electrum wallet, but the old MultiBit has trouble synchronising with network.
Please help - how to move all the BTC associated with my private key to a new Electrum wallet?