It might be an early adapter that only works with Mendocinos. Was a Mendocino one of the CPUs you tried in it?
Have you confirmed this board works with an actual Slot-1 CPU?
Re the motherboard jumpers - they just need to be set appropriately for whatever CPU is in the adapter. Set them for 66FSB with a Mendocino Celeron to start. If that works then try switching to a Coppermine with motherboard jumpers still the same, and work up from there.
If even a Mendocino at 66FSB doesn't work, but the board does work with an actual Slot-1 CPU, then that would leave the adapter as the culprit. In that case look it over carefully for any deep scratches that may have cut a trace.
If this is a Mendocino only adapter then I don't know what the actual difference is between those and the later adapters. Maybe there's a way to mod it, but I have no idea. I wonder what that "reserved" jumper does.