My experience is with the 240 series, therefore what follows may not be exact.

The key Position II, sometimes called "Bulb Test" position, or "Run" position, is well-named either way.

If the key is in Position II, engine not running, the warning lights should be lit. If not, either they all burned out simultaneously, or there's a harness problem.

The circuit that runs those lights grounds through the alternator (except the oil light).

Voltage flows from the battery, through the lights, to the alternator at the D+ terminal, into one brush, through the rotor windings, out the other brush to ground. So a gap somewhere along the way will cause (1) the lights to not come on, and (2) the alternator to not charge.

It's that small voltage to the brush that excites the alternator. Check the connections on the back of the alternator. Wiggle the thin wires, they can look OK and be not. One is the exciter wire, the other grounds the alternator frame to the block.

With the key on, if the exciter wire is grounded to the block, the lights should all come on. Try that to see if there's a gap between the alternator and the instrument panel. (Hope not)

Good Luck,

Bob

:>)