Iso scooter 150 - series 1 vs series 2

 At my initial start of the Iso scooter investigation the following site was very helpful:

http://isomilano.com/

Again I was very suprised to read this scooter was a Maserati spin off. I'm a huge liker of this brand. Also this page described very well the different marketing names provided for the different countries. I'm still unsure how the link is established with South America as a lot ended up there. More surprising is to read that France and Germany were apparently not targetted? 

It also described when the production started and the distinction between a series 1 and 2. 
In my case I was not exactly sure. The advert mentioned 1959 but they also mentioned 1958 and there were no papers with the scooter. As pointed out by the website; the Iso logo on the windshield is perhaps the most visible for a series 2 but mine does not have one. But perhaps it was simply lost overtime, who knows. The other very visible distinction is the extend headpiece over the headlight with the integrated handlebars. 
Upon checking mine, it has a extended headlamp cover but completely different then what I have seen so far. Maybe it was an aftermarket piece but it fitted to good for that. Maybe I had a transition model? After an intense search I finally found 2 online examples having this cover as well. It appeared to be a rare accessoire for the series 1. Hereby an example of a series 1 without and with headlamp windshield accessoire:

Series 2 with headlight cover integrated with the bar handles. In this case you barely can see the Iso logo in front of the windshield. The other visible items are the kickstarter pedal which is longer upwards and also the tail light is different compared with a series 1. Other than that, they are identical. According to the website the engine appears to be slightly different as well. 

In my case there was also an original instruction booklet in French. And it does mention 59, thus hinting towards the second series. But maybe this booklet was obtained later? In any case I expect my scooter was originally delivered in Belgium as on the windshield there was a original stylish logo mounted with the text : "Verwimp - Meerhout". Unfortunately I was not able to reveal anything about this company.