What is this mystery lawnmower

Good evening everyone. First post but not first forum. I purchased a lawnmower from Eb ... somewhere and it was sold as a Qualcast Suffolk Punch 35s. Sorry for the click batey title but ... it's slightly confusing. Well to me a novice. 

Here it is 

Now the sticker on the front says 35s which is good. The info sticker says 35s which is great. Trouble is ... search for one online to get a manual ... including this site and ... well it's don't look like that. 

This also started when I was a kid that grandad had one of the Suffolk punch series. I'll leave it at that because in my research about them to try and bring back those wonderful memories  ... the sound the smells ... mmmm petrol .... I ran into a bewildering wall of info atco amco allet urghhh didn't know up from down by the end. Differing opinions on timelines etc ... so I went for the look of what I remember. Red patrol tank iconic shape ... check. Red engine cowling ... check. Green heavy lump that sounds mouthwatering as it's rolled across concrete ... check and typical 70''s possibly I suspect 80s ... handlebars. .. and here we are with me sat here. That's the first question ... what is it and what era. I've found these bits of info and photographed them if it's any help you guys work it out. Photos to follow ... but there is also a technical issue with the carb I'll also place that at the end. 

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Engine number I assume though could be wrong 

Zenith Carn

Now it is running fine everything works fine it ticks over lovely ... but if the day comes that I need to tune the carb. ... how. And I know the 1 turn 1.5 turns thing I've watched loads of videos in eager anticipation ... but I can't do that on mine. No adjuster on the fuel ... I assume this is the 81 emissions rule but I am clutching there. Mines got a gromit screw in it. 

So how does that get tuned then. 

Finally .. I've done a much needed oil. Change before use. But .... I filled it to the filler hole. No instictions see. It was fuller. Some documents said 0.6 or a litre some said 0.2 ... what fit when level was about 0.2 or 200 mls ... but no dipstick on the lid so had to assume that it be filled level not tilted foward to get more in like the previous filler upperer did. 

Any and all help and advice gratefully received ... the aim is to get one from the 70s. .. it's stickers scream 90s. .. it's paintwork colouring says early 80s to me but pffff I'm guessing really. 

Many Thanks Guys

Matt