The Masterlux was, IMHO, one of the better 3 in 1 cleaners of its time. The pump operates on a pressostat, so you only need to push down and hold the blue button until the pump is primed, after which it turns on and off automatically as you operate the trigger on the handle. I also like the filter setup, which can be used with or without bags.
Mine is tucked away in the garage at the moment, awaiting repair when I get round to it. Sadly the plastic junction which the pump and pressostat connect to has broken, and is of course obsolete. I plan to retrofit a Numatic George pump and connections, which should easily get it back to full working order.
Good score on the Kirby hose by the way. It looks to be barely used, and brand new ones are about the £50 mark. Those floor nozzles are obsolete now as well, but much better than those provided with the later G series.