Hello,
I have a CRAFSTMAN Garage Door Opener part number 41A5021-3C that recently started giving me trouble.
My garage door opens normal, however to close the door I have hold the controller down.
Can you help me troubleshoot it?
Thank you!
Luis

Different models have slightly different characteristics. And some flash they light and/or have an LED indicator that will flash an error code.

But it sounds like problem with the photocell. Wire broken, missaligned, or something blocking the beam.

There is an LED each side. One for the infraread light source and the other for the receiver. Look to see if both are on.

The other thing is that they will stop or reverse if the closing load is too high. That can be caused by binding in the door or opener. Or the sprimgs misadjusted. Or by the opener close force limit mis-adjusted.