Cutting the wires suggests non-stock signals. Do they have dual filaments? How many wires on them? Many single filament units have one wire and ground through the mounting but some have two wires, ground and power. Dual filament ones have either two or three wires, same logic.
Since it worked before with the old signals... either you have miswired the new ones somehow, or they came without bulbs. If not, check the grounding scheme. The stock instrument mount frame or whatever the signals attached to will be grounded with a green wire to the harness as the Stanley originals grounded through their mounting clamps. It's a bad idea to run power through the steering head bearings although it's usually a pretty good connection: the bearings will be slowly destroyed.