The problem is, the door track may be lack of lubrication, too much of track friction then the motor is working harder, and the automatic overload switch cuts out the opening travel. Few things you can try.
1: clean up and lubricate the track,
2: adjust the overload protection knob (it explains in the owner manual) 马力 can not be调整. However, the overload and the cut out protection can be adjusted. The Overload protection is to avoid small child get jammed under the garage door.
3: The counter balancing spring may need to readjust as well.
To determined the conditionof the counter balance spring, unhook the door from the opener's chain.
And open and close the door by hand, if it moves up and down by hand easily without a heavy force. Then balance spring if fine, next thing to do try to lube the track and adjust the overload,
1: clean up and lubricate the track,
2: adjust the overload protection knob (it explains in the owner manual) 马力 can not be调整. However, the overload and the cut out protection can be adjusted. The Overload protection is to avoid small child get jammed under the garage door.
3: The counter balancing spring may need to readjust as well.
To determined the conditionof the counter balance spring, unhook the door from the opener's chain.
And open and close the door by hand, if it moves up and down by hand easily without a heavy force. Then balance spring if fine, next thing to do try to lube the track and adjust the overload,