Suffolk commodor ?

I have inherited a Suffolk Commodor Lawnmower, it is in super condition , unfortunatley it does not have an instruction manual, it starts first time and cuts the grass beautifully ,my problem is I'm not sure about the operating lever as the markings have worn away ,Where can i get a manual ? or can anyone help by explaining this machine . Model No 22A Type75G 14
any infomation would be appreciated.