Thanks so much for the input gents.
Forums like this are brilliant and so helpful.
Having read your comments I checked both the main butterfly & choke shafts and both are badly worn. Looks like I need to replace the carby completely.
Bonnar Bloke, would you happen to know where I could source one / what the part number would be? I'm struggling to determine what would be suitable.
I really want to get the mower running so I can check that if everything's working as it should before I strip it all down.
My preference is to preserve the originality of the mower as much as possible, but if I can't get the Kirby going I may just have to fit a new B&S as a last resort.
Cheers,
mandkn