My middle ages furnace burner wont light.

I have 5 wires on an old mercury honnywell thermostat.

R is hot or power
Jump R to Y starts the AC unit.
Jump R to G starts the fan.
Jump R to W will not light the burner, the pilot light is well lit and burning strong.
O on the thermostat goes to C on the terminal at the furnace?

It is a damper furnace, but I believe the dampers are all manually controled outside the unit.

I'm trying to avoid an $XX service call, like the $XX I spent last summer just to have the tech show me where the levers are and how to move them, I have never seen anything as old as this furnace, except for me that is.

Does anyone have any suggestion as to what else I can try or check before I get the check book out?

(No pricing, due to site rules )

[Edited by jultzya on 10-27-2005 at 11:08 PM]