Several folks have asked me where I found the service manual when I had the DF20A and it was just a chance that a genuine paper coper was on Ebay when I bought the motor. About £20 or so I think.
I think there's a free online copy somewhere on a direct pdf link not a dodgy download... but I can't see it now??
Re service kit I bought from Suzuki UK who were selling on Ebay at that time. I had to get them to list the valve cover gasket as an additional item as it wasn't in the kit despite the valves being a check item and the gasket fitted a single use crush metal type.
All as reported on in this thread which I think you've seen before?