You can tell very quickly if it is siezed up, remove the pull start and if that is ok, hang onto it they are worth more than the mower. I see on ebay all the time where people have pulled the starter off a good motor because they can sell it for more than they can get for a complete motor, makes me cry seeing them destroyed like that. If the motor is rusted, remove all the good bits,coil, ignition module carby etc. This may be difficult for you to get the blade carrier off but depending on where in Melb you are I can get it off in seconds for you if you brought it here. Keep watching hard rubbish they are still ending up there.