My Sherman Filterbank is sometimes sitting for a longer while in the studio without being used. It seems that the potentiometers acknowledge that with degrading contacts and flaky operation. In order to make the Filterbank operate normally again I disassembled it and cleaned all potentiometers with Caig Fader Lube. While doing this I took the opportunity to shoot a couple of photos for documentation.
I also found a very nice switched capacitor filter for modular synth DIY which explains the working principle of the Sherman Filterbank rather well. Here’s the link to the VCF-4 website.
Obsoletetechnology 