If the engine has good compression and the crankshaft doesn’t have a lot of up and down or side to side free play, your mower may not need a rebuild. what you have is a Lawn Boy from around 1979 with an “F” engine...a very reliable and long lasting motor. If you are somewhat mechanically inclined, these mowers are not that hard to work on. I have a feeling that it would not take too much effort to get it running again.
l just finished up refurbishing a mower identical to yours but mine was in excellent mechanical shape. From what I could tell from mine, it was probably used only as a trimming mower. The only wear and tear on it was some scratches and patina from being left outside. The cylinder still had the factory cross hatching and the wheels have little wear—a rare find. All it needed were a few common parts and some TLC. I picked it up in non running condition for $35 and spent another $24 for parts and some elbow grease. When I finished it started on the first pull. A little carb tuning and governor adjustment and it runs like a top. Here is a summary of what I did:
cleaned the carb and the gas tank
removed engine, cleaned carbon out of the exhaust ports and replaced the crankshaft oil seals and cleaned off the greasiness
removed the blade and sharpened and balanced it
lubed the recoil starter
replaced the air filter, carb manifold gasket, and exhaust gasket
removed the spark plug, checked the gap and determined that it was still good and put it back in
replaced the gas and primer hoses
removed most of the rust off of the push handle
As far as value, there are a few things that make these mowers attractive to some—they are light weight, simple, easy to start, they are excellent ditch cutters because the two cycle engine will stay lubricated when operated at an angle, the aluminum decks do not rust away. And for guys like me, I love the odor of two cycle exhaust. I also have a phrase I use often, “If your old Lawn Boy doesn‘t start, it’s usually because of a small and easily solved problem.”
I hope you are able to get yours up and going again. These were wonderful, dependable, long lasting mowers that gave good service with reasonable care. And of course, don’t forget to mix you gas and oil correctly.