
... according to the WinIPAC software.
The software shows all 3 keypresses assigned to 13, all 3 to 14, and all 3 to 16?

If so, that's your problem.

Have you powered down and checked to see if there's a short between the wires?
With the Mini-Pac, wires, and buttons connected the way they are when you saw the malfunction -- but with
power OFF-- use a multimeter in ohms mode and connect your leads to the Normally Open contacts on two of the three microswitches.
They should register as open.
Repeat with the other pairings until you've tested 1+2, 2+3, and 1+3.
If it shows up as a short, unplug the cable from the Mini-Pac and repeat.
If it still shows up as a short, it's the IDE cable.
Scott