Hi,
I have no idea what brand knob this is... that was a knob I found in my "this & that" box with all kind of stuff in... it's some replacement knob I assume I bought here in Germany in an online shop... I am sorry I have no idea whether it would fit onto a Junior... I would think so... maybe you have to enlarge the hole of the knob a bit or squeeze the two bits on the axe of the pot a bit - very carefully.
Greetings
PIT...