don't ... install a new crankshaft on their mower if they don't know what they are doing, don't know if they have all the tools required ...

Sorry, but you've disqualified yourself for any but the extreme lowest grade of ol' man. (we still call them "the young 'uns.")

A PROPER old man has all the tools anyone could possibly need to do anything that can be done. And in addition, probably can do almost anything you can even think of doing, with nothing more than a pocket knife with one old loose blade.

Even if you had scant possibility of a successful repair you missed a splendid opportunity to honor your TAS, by getting at least a dozen "tools you might need" before even starting to take anything apart. (Since the important part is the excuse for getting the tools, you don't really have to get around to taking anything apart once you've got them.) You could certainly have enhanced your "old man" reputation just by having a proper "kit."

Once you've reached the stage of old manship at which you have more tools than you can ever possibly use, the only remaining grades of old manning are the next - having all the tools but not remembering where "the one you need" was put away - and the ultimate grade of having all the tools, organized so that you can find them all, but not remembering what most of them are for. (except the pocket knife, of course, even if it's only use is for carrying around "in case you need it").

John