Oooohh I love the Panasonic 40 series! I grew up with one. They're one of my all time favourite cleaners. Very lightweight, strong suction, easy to use and very reliable. We had ours in daily use for 17 years.
They were launched in 1986. It was one of the first uprights in the UK to have on board tools. The first models were slightly different, having the older style brushroll as was found on the earlier Jetflo and a smoked clear plastic tool cover that was prone to breaking. The earlier models also had a 600w motor.
There were various minor changes to this model between 86 and 88, as these cleaners got more and more popular. In 88, the 41N, 42N and 43N replaced the original lineup, having a 650w motor and coming with an extension hose that was optional on the 41 and 42. They were upgraded again in 1992 to a 700w motor as the 44, 45 and 46.
They're really fantastic cleaners, but if you're expecting something that's going to lift the carpet off the floor, this isn't the cleaner for you. The brushroll is fantastic and does a great job, and they're also one of the few uprights that clean right up to the edge. But they don't suck the carpet up. They never really needed to, to be honest - they do a good job without having to lift the carpet clean off the floor.
Re: the end caps. There was a bit of a drama in the early 90's on Watchdog with children sticking their fingers in the vacuum. After that, Panasonic started fitting thin end caps. This must've been around 1992 as the larger 50 series was launched and that included end caps from the very beginning. Quite frankly, if you're dumb enough to let you child stick it's finger in a spinning vacuum brushroll, you shouldn't be having children in the first place.
The 42 in the link looks to be in good condition, although the dusting brush shouldn't be stored like that and there's no sign of the upholstery tool.