I have played this game before all tbe way through but this time I am stuck trying
to leave the city to get eggs. The small dyno is jumping outside the power wheel,
I don't have any fruit to entice him, and nothing I do will get the cart moving.
I can't get more tban one fruit from the tree, there is none to buy in the market, so
how do you get the dyno back into the wheel?

None of the walkthroughs even discuss this issue and imply that the cart is ready
to go as soon as you leave the city gates.

Hi Robert, good to see you - it's been a while.

I hope what you are describing isn't a glitch of some kind. If it is, maybe restoring an earlier save and playing through to this point to see if the same thing happens would be useful?

I haven't played the game so can only refer you to video walkthroughs on YouTube and written walkthroughs. If you need any links, please let me know. Otherwise, maybe another player will be able to help you out here.

I have actually reinstalled the game as well as starting from
a previous save. Nothing I've tried helps.
I don't think it is a glitch as in the past I've gotten past this
point in the game. It would help to know what other people
see when coming back to the cart. Is the small dyno outside the
cage? Does it matter if you have not done something in the city?
Can you get more than one fruit from the tree? Can something
be bought in the city to entice the small dyno?

There are walkthroughs on YouTube that might show you what other people see when coming back to the cart. Here is one such walkthrough.

I finally found what was "wrong"! You could
Call it a discontinuity in the game plot.

It turns out that leaving the gates and going
to the cart automatically returns you to where
the tyrano was without a video showing you
riding the cart. Then clicking on the cart returns
you to the city gates without a video of you
riding the cart.
You don't need fruit nor getting the dyno into
the cage to take a ride.

I'm surprised that this is not mentioned in the
walkthroughs.

Actually, I think MaG's walkthrough does mention there not being video for that. I had been looking at the WT trying to refresh my memory of the game and saw something about that.

Glad you got it sorted, Robert. Enjoy the rest of the game.