If the burner goes on reset on a regular basis and you aren't an experienced burner tech it could end up costing you much more doing parts replacement on a guess than just calling for service and having it done right.

Some problems are very simple to fix and require no parts change, others aren't so simple. Something that you can do yourself that would be of help to a tech would be to watch the burner go through some cycles to determine if it locks out during a long run, if it starts but doesn't fire, it fires but locks out at the end of trial for ignition or if occasionally the burner doesn't start when it should then it just locks out.

The primary control is causing this. But why? It could be a clogged oil filter, smoky flame, dirty nozzle, an obstruction in the chimney/vent.... When was the last time it was serviced?