Joe Lennox writes:
When things aren't working, the first fan comes on, but there is no click
and no ignition.

One gentleman said it needs a new ignitor, which sounds reasonable to me.

If there is no click and no smell of gas, then the furnace is
never getting to the point of trying to use the igniter,
which means that it's the pressure switch or something like
that, not the igniter.

For some reason the furnace control module doesn't think it's
safe to turn on the gas and ignite it.

If that's the case, then I'd strongly advise you to pay a
professional to troubleshoot and fix the issue.