[Boater Sam]

I see nothing wrong in adding the components if it enhances the radio's performance.
I am prone to making small improvements myself. It has saved the cost of a new control and there is no knowing if a new pot would not have gone the same way. It takes very little DC current to cause the crackles.

The "missing" grid stopper and coupling capacitor could well have been a cost cutting measure by the makers anyway.

There are those that would disagree, but its your set, its better than it was before, and its your choice.

Sam.