Hi, I’m pretty sure it was just a 100k pot.
One thing you should know is that this mod works on my freebass because the eprom and midi part of the device is completely broken. If your freebass is fully functional then you’ll also have to stop amp midi on/off messages. I found this out through correspondence with another owner of a freebass who was doing mods. I however do not know how he accomplished this. his note is below.
…”your section about filter trigger (zero ohm resistor) was right, but not quite. As in fully working unit i need to open not only filter (zero ohm resistor mod which stops envelope to fade out) but also need to overcome amp on/off midi messages, so i combined those to point to one switch. Now i have legato notes when the inner osc is on
”.