Creek 4040 Amplifier blown some speakers ?

Question

Had my Creek since 1984 - absolutely brilliant !! However, I think something has gone phut and blown my Mission 70S's.
When the speakers load after power up, they rustle badly and hiss like excessive static, then they don't play anything.

Just bought some new speakers (AE Evo1 Aegis) and have tried connecting them to the Creek, they rustle very slightly but hiss over the music. Need to fix this before driving them for real.

Any ideas would be much appreciated - the amp is too good to give up on.

Thanks in advance, Chris