That is a Tecumseh engine.
Thats just the inlet manifold part number.
The Tecumseh motor just has a sticker on the metal cover. Yeah stupid i know, dumber than the stamped on a briggs cover which is a bit silly as well. How hard is it to put it on the engine block.
With the Tecumseh at a glance you cant tell a TSV90 from a TSV120 if its not all dressed up.
Step by step.
I dont mind offering advice if you would like to tackle it yourself, however if you have no mechanical aptitude i would suggest you do not even try. If you hurt yourself it is not my fault.
Get some degreaser and wash the mower. Leave it in the sun to dry..
Go and buy a new air filter (take yours as a sample), blades, spark plug and oil.
Use degreaser on that foam (well its more like plastic) pad in the air filter housing. Wash it up all clean and let it dry. Not 100% sure but i think its meant to be oiled when it goes back in. A little bit of engine oil, squish the foam, blot it off with a clean rag. Needs to be moist with oil, not dripping.
Do you have a socket that will fit the nut on the blade plate??? On that it should be 3/4".
Clean rope in the spark plug hole and gently apply pressure to undo the Bolt, undo it. Doing it up you need to go through 360deg to bring the piston back the other way so it will lock against the rope. A bit of care not to feed the rope up under an open valve.
Not sure how you will get the bolt tension right. Dont over tighten it, the bolt will stretch and break.
From bunnings you can buy a Victa brand oil suction bottle, its in the mower isle. For $20 its a handy bit of kit, sucks the oil out through the fill hole. But with the disc off you can just use the drain bung.
To get the blade bolt nuts off. Try standing on the disc foot either side of the nut, with the head of the bolt on the concrete, you want to hold the head of the bolt hard up to the disc. Undo the nut. Undoing it with a rattle gun is easiest.
If the bolt head spins, cut the nut in half, cut it from the top, along the length of the bolt the full depth of the nut. Dont try and cut across the bolt.
Clean the blade plate, check for damage around the bolt holes. Put the new blade in the vice, clamp the cutting edge up tight. Put the bolt through with the plastic spacer, put the disc on then the washer and the new nut. Holding the bolt into the disc do the nut up with a spanner. Its only meant to be 15nm or so and that is not very tight, easily achievable with a spanner. Do the same for the other blade/blades.
I would remove the carb and manifold.
Pull the carb off and clean it out. Before you do, crack the head of the main jet that holds the fuel bowl on. Or you can tip the carb upside down and hold it in the vice using soft jaws.
Looking at the pic i think someone has messed with the fuel bowl, the gasket does not look right.
aerosol of carb clean is handy. So is compressed air.
Pay attention to where the linkages etc go, take photos.
While you are doing this its a good time to check the valve clearances.
If they are tight you will need to remove the head to be able to reset them. Remove the valves and grind the end and refit.
