Door stops and reverses when opening, opener flashes four times, display shows code 4.

Safety first: Disconnect power before adjusting hardware. Do not operate the opener with a visibly damaged door.

• Inspect top section: Check the top panel where the Merlin opener arm attaches. Look for cracks, bowing, or loose reinforcement strut. Tighten mounting bolts and replace damaged struts or panels.
• Check header bracket: Ensure the opener header bracket is firmly attached to solid framing and not flexing. Tighten lag screws or relocate to a stronger point if necessary.
• Align opener rail: The rail should be level or slightly sloped down toward the opener. Adjust hanging brackets so the rail is straight and not twisting the door.
• Inspect tracks near header: Look for tight spots or misalignment at the top of the vertical tracks and first curve. Loosen track bolts slightly, tap the track into correct alignment, then retighten.
• Adjust UP force: Using the Merlin control panel or force dials, increase the UP force slightly following the manual. Test after each adjustment.
• Run a full cycle: Restore power and test the door through full open and close. If the opener still strains or the door sticks, have the door hardware serviced.