This is a very basic question. We have a GUCA090AX40 Amana Furnace and the blower motor seized up. It looks like the blower assembly should just pull out. There are no screws that I can see holding it in place. I don't want to force it out and damage anything. Is there a screw or retainer clip I'm missing?

Usually there is one or two small sheet metal screws at the slid in top bracket or on the slide rails. Some units might be different.

Often there is a hex screw hiding in the back and you need an inspection mirror to see it. A flexible head to get it out will save you a trip to you chiropractor afterward.

If you can confirm all are out like hvac1000 said it should slide out real nice just unload the weight of it as you slide it.

On this model there are 2 hex head sheet metal type of screws at the front top of the blower unit. Take these out and the blower unit will slide out.
But first you have to remove the sensor that prevents the blower unit from sliding out. It pulls down and slides to the right. Then the bracket slides off to the left. Disconnect the cables that are plugged into the control module and the blower unit will slide out.