DSL50: presence & deep switch not working

[warioblast]

Hi guys,
after many unsatisfying attempts at gutting my DSL50 chassis with a plexi style turret board amp...
I decided to assemble back the parts of my DSL50. I took some gutshots of the DSL50 in stock from a few years ago.
I put it all back together a couple of days ago.

Everything is working except for the presence & deep switch. I googled this problem, but I only find one result.
Following the comments on this page I checked that the connectors and ribbon cables from that part of the schematic were fine.

I reflowed the solderings from that portion of the front pannel board (61-00).
The presence pot reads fine. I tried a different cap for C30 (on the front board).

I turned the amp out loud. I could hear the background working noise becoming slightly treblier as I turn the presence pot.
When I push the deep switch, I also can hear a tiny hum happening.

I do read around 44k between the 4 ohm pin of the output transformer and R43 10k, on 61-00. (bottom right arrow).
Top right arrow is showing the 47k feedback resistor (R19 on 62-00).

I tried to wire a 5k pot and a 100n cap, like a 1987 / 1959 marshall, between this feedback resistor and C30 R55 R66 & C29 (main board 60-00). All I could hear was the scratchy pot, not effect on tone.

 

[warioblast]

....

[warioblast]

I reflowed a few solderings around C29 on the main board.
Deep switch & presence pot are working. The deep switch is more noticeable.
I can hear the action of the presence pot but it is rather subtle. It's been so long since I have played with this amp, maybe it's normal.