How do you reset the service light on the 940 volvoafter an oil change?

Below the speedometer there are 2 reset buttons. The one that sticks out resets the odometer. The other one is under a little rubber plug. (If the plug isn't lost) Pry out the plug and push in the reset button. The button can be pushed through the plug, but sometimes the plug ends up inside the cluster. I just take out the plug and throw it away.