As stated, my heat isn't coming on.

When this started:
Everything has been all fine and dandy all winter. The other day I ran the fan only for a few hours without the heat.
After this, my heat would no longer turn on.

I figured maybe my pilot light had gone out, so I went and checked. Turns out I have an electric pilot light.

I've done some troubleshooting already.

-10A round fuse on the side of the heater is good. Replaced it with new just to check that off.
-Breaker was not flipped. Cut power and reengaged power just to check that off.
-Thermostat can engage the furnace fan by setting it to "Fan On".
Setting the heat causes it to call for heat (click noise). Heat does not come on.
-Gas dial on inside of furnace is set to "on". I turned it to off and cut power, then reengaged everything before trying to call for heat from the thermostat just to check it off.

What am I missing here? Could something have failed while I was running the fan?

I have a Trane model BLU068L942A1. Probably from the 80's.