Do Lionel 60 (trolley), 50 (gang car), and 51 (navy yard) always run hot?

It may be the brushes. (I assume that when you wrote 'bushings', you meant to say 'brushes': the small cylinders which run against the spinning armature). Some have had trouble with new replacement brushes making the motor run hot. More info in this thread:

https://ogrforum.com/...lionel-motor-brushes

You're right, brushes. They were running hot before I changed the brushes,  that is why I changed them.

I have been waiting to see what other folks have to say.

If you haven't done so already, I suggest you read the thread linked by NICKAIX.
I am not certain when they crept into our supply stream, but many of the replacement brushes out there, including those sold by Lionel, have excessive resistance.  The more resistance the hotter the brushes / holders will get.

I check the resistance of every replacement brush before I use it.

For many years I would replace original brushes as a matter of course when I serviced a used train for the first time. When purchased in bulk, they were just too cheap to leave the old ones. Now that the quality of the supply is in question, I am less likely to do so.

Have the same issue.

can someone provide a good source to order the brushes?

thanks in advance