Unfortunately, appliances aren't made to make it easy or practical to replace these thing.

.. though that doesn't usually stop on its own then reappear.

It's really easy.

A DIY'ers dream. You get to play with simple plumbing under the sink and deal with electricity!

Can I use it till it quits or is it better to just replace it since I will need to eventually anyway?

Be sure you have a good circuit breaker, or if you have glass fuses that you don't have more than a 15 amp fuse there.

I mean to say that the only danger is an electrical overload and fire incident.

Kind of makes replacing the unit sound like a good deal, no?

If it was me, I'd take out the old unit and bring it with me to make sure I'm getting a new one with the same features and rough dimensions.

In advance of doing that, you might find the hardest thing to do is to remove the existing unit- Here are two useful YouTubes:

But yes, I will look at getting it replaced, soon. I know this is probably a simple task for those with the tools, but to me it looks like 4 hours of aggravation, frustration & a reason to drink heavily afterwards.

Thank you!

and these 68 year old drains probably wouldn't handle one very well, so I've avoided having one.

However, if the cheap and obvious part of having all the screws tight is not the problem, you're probably looking at a bad bearing.

The choice is a high labor charge for rebuilding it or a lower labor charge for a new unit--or just dispensing with it.