One of the books from Guy Fay has a list of what things were masked before painting. The actual list probably changed some over time. The masking as done on the line seemed to be a little haphazard. Masked items included: magneto or battery ignition unit (and I think plug wires), light and gauge lenses, serial tag, generator and starter tags, fuel sediment bowl glass, electrical connections, that was about it. Some things were not installed until after the tractor was painted: lights (after they got Guide to supply them in red), steering wheel, seat pan, tires and rims, wheel weights. The curved guide part next to the Touch-Control levers probably belongs on this list as well.
This doesn't apply to the Super A. The straight rear axles that were used with clamp-on adjustable wheels were not painted (were masked). Paint would make track adjustments very difficult. They were black and did not rust for years. I assume they were Parkerized or given some chemically similar treatment.