What can cause a roll out, the switch keeps tripping? The roll out can be seen but the exhaust blower is working. The heat exchanger is not cracked, I had it checked by the local gas company.

The roll out can be seen but the exhaust blower is working.

Just because the exhaust blower is running does not mean it is exhausting the correct amount. You could have a partially restricted discharge vent that will cause that problem. You gas valve itself might need to be adjusted or a variety of other reasons.

In order to test your equipment you will need various meters and the manufactures specs to be sure all is set for proper operation. Delayed ignition is another problem you could be having which can cause roll out during initial firing of the unit. Also a slow to respond or defective pressure regulator can cause your problem also.