1928 is a tricky date, there is an early and a later version of the knee lever and I think the way it is stored in the lid. My 1934 99K has the later type knee lever. If it has knee lever base and electrical motor, I guess it should have all the fittings for the lid. Later on pedal became more common, but both options remained common a bit ino the 1950s, at least for bent wood models made in the UK factory.