Hi, I have a DW-8000 that my brother and I got new when they first came out.
About 25 years ago I noticed the volume slider didn't make any difference at all. Which was good, if something fails I'd rather mixing it externally than nothing at all.
Oddly some months after I also noticed there was no reverb / delay. By this point I had hardly used this board for anything but a midi controller anyway as I had migrated to sound modules with 16 parts.
Are both the volume AND reverb residing on the same board? I have an opportunity to buy a delay board. Not sure it's worth buying if it only fixes delay and not volume. But knocking both out would justify the cost.