What'll it do mister?
There are no certainties in this life. All we can do is work with the best we've got, and to the best of our ability. When you work with old vehicles, you are left with a hell of a lot of choices. Replace everything for fear of something breaking down the track, or use experience to decide what will keep going, and maybe rely on a little bit of luck. It's probably fair to say we use all of these methods without a second thought.
It would be nice to change every bearing, gear, thrust washer, bolt, moving part etc., but that generally isn't viable. Instead we check, measure and work out what we can get away with. Lots of parts aren't even available anyway so sometimes we are stuck with far greater tolerances. When there is wear in vehicles, we immediately feel it when we ride or drive them but, as human beings, we automatically adjust to cope with the discrepancies. Some better than others.
Sure it's nice to be on a brand new bike, where everything is perfect, but they also leave me feeling somewhat robbed (not just with the cost of them either:). They let you get away with things, incredible brakes, plush suspension, tyres with more grip than you know what to do with. You may even think you're better than you actually are (oof, perish the thought!).
But with old stuff you feel everything that is happening, hold the bars too hard through the bends and the weaving starts, fight it and things get worse. But relax and let it work everything out for itself and they usually settle down quite nicely. You feel that you're achieving something, that a living being is out for a blast with you, stirs the soul don't they say? (It does get tiring though...)
So ladies and gentlemen, just once, get on an old bike and be amazed at what they will do if you're just prepared to put in the effort...