If it gets worse then it will be more obvious what is wrong. You could just check the obvious by getting someone handy like a teenager with a motorbike or a guy in a tyre fitting place on the street etc, to grab a wheel and rattle it back and forwards to see if theres any free play, check wheel nuts and look for the obvious just in case. Anything deeper would involve the sort of thing you cant do. And that would mean a bit of major surgery... At that point you may as well wait and see if it gets worse or goes away...
Me? I keep sets of spare motors on the shelf, and spare chairs sat around. Just in case. And if I hear a funny noise I take things apart to investigate. Not everyone can do that. Ebay is your freind. In advance. But if you cant investigate

you also cant swap a motor... I cant either, but I can delegate! And have carers, nephews, etc.
I see, well with the nerve damage I have I can't really do all that.
If you dont have anyone to help, then do the following (as I
also do just in case!)
I got a bit of paper through the door the other day. As I often do. Or a business card, flyer etc.
Some I keep.
In this case, from a keen 16 year old. He wants to wash cars and says he likes cars! And a DIY printed "leaflet" shows him to be keen and @ £10 a car... Most young people are lazy and dont want to work. This one is different. I already like him! In your situation I might call and ask if he is interested in learning something new. And helping you for a few £££. But thats because
I already have spares, and tools, etc.
I kept his scrap of paper (as well as 4 or 5 similar ones in the last year) in case I need someone useful to help me do cars, chairs, gardens, cleaning drives, DIY etc. Because you never know.
Think laterally!