Hi OF,
My first port of call would be the engine and to see if it was worthwhile salvaging or simply swapping it out for a new power plant which isn't that expensive now a days.
Is there a good amount of compression, pull rope starter and see how much resistance there is.
Secondly how much sideways free play is there in the butterfly shaft on the carby. That's the one with the plate on top with a rod connecting it to the governor lever. If there is a fair amount of wiggle in it then that shaft is a scrapper and new ones are no longer available. It's easier to buy a replacement carby off eBay and replace the whole unit opposed to messing around with an old worn out unit that will leak air and give the engine a hunting effect while it's running.
Apart from that it's a full strip down for this particular machine as it's been sitting in a corrosive environment and just looking at the reel, rear roller and the engine tells me a fair amount of work will be required to bring this one back to it's former glory. That being said it's all just time and effort and you'll be surprised how well it will shine again.
Cheers,
BB.
