On the rear of your motor unit near where all those white wires go you will find two controls. One is the 'up force' and the other is the 'down force'. Turn the 'up force' about a 1/4 turn clockwise. This control will compensate for springs that are weakening due to age.

Try the door by hand after disconnecting from door opener. Make sure it will open easily by hand. If not, then get service on the door springs. You will damage the door opener if you continue to try operating this with the door opener. Also do Dons Post... Dan