Thanks Jack, You have provided some excellent information here. Yes there was a lot of drag on the KXD blade plate. In fact when I first looked at my dad's old KXD-2, I found he had been using some very long bolts that he must have purchased from the hardware store. He had put two nyloc nuts on top. So the whole thing, with the bushing, was around 5cm long, making for a huge amount of drag. I guess the hairline cracks I found in the disc around the bolt holes were a testament to this fact. I've since found some shorter high tensile bolts. I got the blade plate welded up and the welder assures me it will be stronger than original. My chances of finding another blade plate in good condition will be very slim and there do not seem to be any suitable modern replacements.
The original design of the KXD blade plate obviously relied a lot on those nyloc nuts, with just a round bolt and washer in between. But I can't say I ever heard my dad complain about bolts coming loose or falling off. The Howard blades that he had on there were worn down to about half their width! The bushings on the plate are still original and do not look to be very worn either.
I can relate a funny story about the blade plate. When the welder started mending the cracks, all of a sudden the bushings dropped out. He wondered what was taking place. Evidently they have a polythene cushion around the bushings and these melted on heating and released the bushings. Luckily he had some thick poly on hand to re-position the bushings when he had finished welding. I'm not sure if some kind of polythene or nylon material was used originally, or if this was brass or some other material? I can only guess that the bushings were designed to move, so the blades could swing back if they hit something hard.
