The
Dual sanitronic 50, ds 80, kirby classic and some classic omegas used the same safety switch. The second safety switches are in short the same. If the kirby was in for repairs and be switched easily. The nozzle only works with the first safety switch. It has the safety switch and the nozzle which is likely no coincidence. This more than likely was a 1980s kirby bojack special.
You can wire the vacuum bypassing the safely switch making the vacuum to power on and off by the power on and off.