I'll just address the engine issues Tom, and leave the mower frame issues to Deejay.
Your engine is a side valve 4 stroke, of 100 cubic centimetres displacement. It requires ordinary unleaded petrol of 91 octane, with no additives, and no oil in it. Do not use 2 stroke mix. Do not use petrol containing ethanol - it slowly damages some of the fuel system parts.
Remember, because it does not have oil in the fuel, the sump must be kept full of engine oil. Check the oil before trying to start the engine.
Real petrol, without ethanol or ether in it, can last a long time - I've used petrol that had been in a jerrycan for more than 5 years, and found no difference between it and new petrol. However petrol containing ethanol gradually absorbs moisture, goes yellow, and then does not operate the engine's carburetor properly. Because we do not know what kind of petrol is in your engine's fuel tank, it should be replaced - but draining the tank properly requires taking some of the engine to pieces, which should not be done unless it is necessary. You could siphon out as much of the old fuel from the tank as possible then fill the tank with new petrol, but it is probably more convenient to just check the colour of the fuel you have. If it has gone yellow, or if it no longer smells like proper petrol, it will have to be drained. Remember, petrol is a hazardous material. It is toxic, irritant, and explosive. Please do not disturb the fuel until we talk about how to handle it safely. Just remove the tank cap, look at the fuel, smell it, put the cap back on, and report back.
