Hello, I am a retired lawn and garden technician. If your equipment needs some attention. Yet the repair shop you have used in the past. Inflation has raised his labor rates to the point where it is cheaper to just buy a new one. Sometimes that is the case. Lawnmowers are generally put to the test. They operate in a high-dirt environment. If they do not receive proper service attention. Then the life of that engine can be very short. The first thing that needs to be done is a walk around. You want to look for signs of oil leaking. and where it is leaking from. What kind of shape the blades are in. Do the blades have grooves worn in them? is the outer cutting edge worn to a radius. check the blade tips on multiple blades even when brought around to each of them. If they are not even. Is it the blades or the blade spindle pocket that is bent? Is there a large amount of grass clippings stuck to the bottom side of deck? Too much build-up will take away the amount of vacuum the blades produce. The  Vacuum is needed to lift the grass up to be cut off. the belts should be inspected. Looking for cracks, splits, and burn spots. Anything that may cause the belt to break. Checking bearing failure from a dry bearing. If a pulley is spun and growls at you. It should be replaced. Look at tires and check psi. Uneven tire psi will cause an uneven cut. Check the battery voltage and battery terminals for corrosion. The charging system should be checked for proper function. Should be able to make a parts list that will enable you to complete the services from here.

The Engine:
Air filter paper:  When you shine a light from the inside of the filter to the outside, There should be a white clear light shining through. If there is not or the light is dim it should be replaced. If spark plugs are corroded it is best to replace them. Check the air gap on the electrodes they should be .30. Fuel filter should be replaced at least once a year, drain the engine oil, and replace the oil filter. Refill the Crank-Case when done draining.

Hydro if equipped should be checked every 200 to 500 hours. depending on which hydro is used. refilling a drained hydro requires a vent plug being removed and air bleeding done. This may need to be done with supervision if you have never done this. If not done correctly you will burn up a hydro.

Grease the machine level deck and check the tracking on Hydro unit you are ready to mow.

You are looking at about 3 hours to complete the service. If there are some belts or bad bearings that need to be replaced. It will take longer