Canadian Marshall 4010 from 1984 Impedance Switch Help

[splitslim]

Hi there,

I'm bringing this amp back to stock form and would like to rewire the impedance switch back to stock, removing the 2x3300pf caps connected in parallel between the NFB purple wire and the 4 ohm yellow tap wire (bass boost/resonance mod?). First question would be - should I be removing this? The amp definitely gets full of bass when at noon and above on the bass pot.

I'm confused how this switch would have been wired originally. Being a Canadian model, there is no 16ohm tap or wire and I can't find a similar one online to copy in stock form.

I want to reconnect the purple NFB wire to the yellow 4 ohm tap, but am not sure why the purple wire is currently connected to the top lug.

Here's a pic of the current state;

https://photos.app.goo.gl/X42hcnskYrwaM6BPA