[protonimitate]

> ... as they have worked together for quite a while without any substantial progress on the juniors side.

Seems like a misalignment on ability and expectations of the jr. What is "substantial" progress defined as? Was that definition shared with jr? It's hard to make progress towards something if that something is nebulous.

>He seems motivated to learn but has a bad intuition on how to do things the "right" way.

What is the "right" way in context? Is it the difference between a non-working and working a solution? Or is the difference between a sub-optimal solution and the best possible solution?

To me this sounds like an ideal jr hire. Eager to learn, and still green. This sounds ultimately like a case of poorly defined expectations.

What do you expect the responsibilities of the jr to look like in 6 months? A year? If you start there you can work backwards and help set smaller goals.

Without a strong idea of where you want them to end up, you're just asking them to "get good" which is bound to be frustrating for all parties.