What to do with a TT2?

[YNWaN]

This is an extreme picture, but it shows that the belt will almost always be on the verge of the pulley, top or bottom.

Why do you say that this is an extreme picture? The belt is riding in, essentially, the correct position.

Below is the pulley from the early TT2:

This has convex belt surfaces and flanges to prevent wandering. It's quite easy to adjust this one to perfect running.

To be honest, I don't see how one is easier to adjust than the other? A strobe is required for the first, but at least it directly adjusts the speed (by adjusting the effective diameter that the belt sees).

I can appreciate the desire "not" to use a convex pulley as imperfections in the drivebelt will always create speed variations to a bigger degree that with a straight pulley... At least imo and theories!

No, there is no inherent disadvantage to a crowned drive pulley.

So, what is the best way to make the belt stay on the flat portion of the pulley on the later version of the TT2?

Both the drive pulleys you show are effectively the same thing, crowned pulleys. The only difference is that the first allows the profile of the crown to be altered by tilting the vertical axis of the motor relative to the plane of the belt. The second assumes that this mechanical adjustment will be made electrically. Neither pulley solution is better, or worse, than the other in mechanical terms as both achieve belt centring my the same method, and a crowned pulley is the best solution.

However, if everything is accurately machined to a sufficiently high tolerance and the belt produced similarly, belt wander should not be an issue even on a straight sided pulley (unfortunately this is not always true, even for many 'quality' turntables).