Hi John,
nice pictures! I only have that Bub with a clockwork engine, these were and still are quite common, as they were the cheap ones in toy train world. They (the clock works) must have been a real frustration, as they run away like a rocket, and derail all the time.
The electric must have been a big improvement I guess.
Your Lionel: I have that too sometimes. But that's the carbon sludge on the commutator I think. By pushing the engine the commutator moves, the brushes picking up a not so dirty spot, the motor starts to run and the spinning commutator 'neglects' the filthy spot, as long as it lasts. Cleaning with a cotton slab and alcohol will do, and fresh brushes too.
I don't know exactly the type of the Bub reverse. It might be the copper 'fingers', may be there's some corrosion. Be careful with cleaning, they are easily bent. Don't sandpaper them or file, that just scratches and dirt will stick on it easier.
Some of these reverses have two very small springs, may be they are a bit overstretched by age.
I think the clicking is the magneto, trying to shift the contact fingers but somewhere the contact fails. It's like the Lionel reverse, the magneto driven hook just doesn't snap the cog wheel, the hook falling back again, without result.
Putting power on and off quickly usually does the trick, sometimes you have to do that a few times. Considering the age and quality of these engines, one can't have to high expectations I think. And even my better quality Marklins, and Lionels do stutter every now and then. As a kid that made me furious, now that I'm old and slow I can live with it.
Have fun! Kieffer
PS My 'advice' is from the players view, the try and error. I'm not an electrician, other people on this forum surely can explain that aspect much better than me.