Smr voicecard. osc's work. filter dead

I have an smr-4 card where everything works except filters.
Turning the filter does nothing. Trimpot does nothing.
Where to start troubleshooting.

Post a high res photo here from both sides of PCB.

Thank you Adrian.

Here’re the photos. I should say the filter was kinda working until recently. It had about 10% of the regular filter range and the card produced a garbled sound. Now I can hear the osc’s clean and filter has no effect whatsoever.

I didn’t build this myself and I have some ( but very little experience ) soldering.

Hmm, the soldering is not pretty …

Simplest thing to do first: reseat the ICs. You might not have to take them out completely: press them firmly into their socket. If it was working, an IC not seated well could wriggle itself out a little more.

If that does not help, take them all out (make sure you make a note which one sat where, or use your photo!) and reflow the soldering of the socket pins. These were not done very well, if you don’t mind me saying …

Looks a bit like a too cold soldering iron, or too little time to heat up, at least to my eyes.