Hi
SimRice,This is one of the mysteries of the Scott Bonnar saga, and the reasons behind the design decisions remain just that...lost in the mists of time....and no records exist.
The solid deck 14" cutting width machines had the counter-weight to assist with the turning capabilities of the machine..(ie. the differential action of the split rear rollers) and the 20" machines of that period had a 3 segment rear roller (the middle one was 3" wide so as to be able to use the 2 outside rollers from the 17" machine) and most probably needed the counter-weight for the same reason.
Your machine is a post 1976 Series 2 twin rail machine and was the result of a design change....(and in my opinion) was a cost saving exercise...delete the solid deck, substitute the engine deck with 2 welded rails,
maybe delete the counter-weight, and only produce the 17" and the 20" mowers (the 14" being deleted) and increase the price of the machines, to the public.
Just my thoughts,
