Well the good news is I was able to replace the throttle successfully, even though the one I got online came with the wrong connectors.
I have discovered other problems, so the electric bike is in the midst of a major overhaul. While looking at the front wheel, pondering whether to upgrade the spokes (one is broken), I noticed the hand-me-down tire is beginning to burst at the seams! This could have led to an ugly accident, if it blew in traffic.
I just ordered some new Schwalbe Big Apple tires (they're said to have some ballooning suspension feature, and my bike has no cushioning whatsoever right now), some new DT-Swiss spokes (in black!) in 191mm length and 14 gauge (based on hours of Internet research; originally the Crystalyte hub probably came with 12 or 13 gauge spokes but of a lower quality manufacture). I also threw in some bottle cages and bolts for good measure.
Combine this with the rack I just replaced, and you can see this little beauty has been an expensive proposition. I'm also starting to think about new batteries. In fact, I am really starting to doubt it's been cheaper than driving this past year. The main financial savings is in the capital cost, but I've probably exceeded $1,000 in total expenditures on it so far. Still, it is easy to drop a grand on a single car repair.
It is a good time of year for the bike to take a little vacation. I might still bring out my conventional mountain bike. Gas is cheap and I am lazy, however.