My lawnmower that I bought in 2001 was ready for the tip as the deck had rotted through. After a while looking on
ebay I found one, the same mower but with a cosmetically different deck (but the same dimensions) and a different engine (Tecumseh Vantage 35). I got it delivered for £35, which was a bargain. The engine on the new deck had a broken recoil starter. I know nothing about these engines and couldn't be bothered learning. I swapped the Briggs & Stratton Classic 35 over to the new deck and the handle and a wheel that were damaged on the new deck. The blade had to be removed and was sharpended for the first time in 20 years with an angle grinder flap disc. The governor springs, air filter and engine oil were also replaced. All other useful parts were taken off the old deck for spares. A lawnmower like this these days, with a metal deck and a decent engine would be over £200, probably have a quieter engine and maybe a touch lighter, but that doesn't really interest me at all, I'd also imagine the engine would not be as simple and last forever, but could be wrong.
The new deck has hardly any rust, so if I look after it better than I did the last one, hopefully will get another 20 years. Just need to clean it more and apply ACF-50. The Briggs Classic 35 engine is so reliable, apart from servicing (which didn't happen as often as it will now), it only required a couple of £2 carburetor diaphragm's in that time. I'd imagine a lot of these go to landfill for such a cheap fix.
This guy has an awesome Youtube channel when it comes to fixing engined mowers, always been a big help.
Repairing Lawn Mowers For Profit
The Tecumseh Vantage 35 engine I couldn't be bothered with. Better external condition than the Briggs. Might try and sort it if the Briggs ever explodes. Apparently the Tecumseh is a lot harder to get to the carb and set it up etc, whereas the Briggs is simplicity itself.