Steps for Replacing Slide Motor

I have a 2006 Fleetwood Pace Arrow 37C. I have three slides, the bedroom, Kitchen and dining/living (big slide). My big slide is not coming out. I checked the fuses on all three of the slide controllers and none are blown. I then identified which ones were which and I was able to test the 'big slide' controller by connecting one of the other slides to that controller which is fine. I then tested for voltage to the motor and that is good as well. I now know that I have a bad slide motor. Before I release the brake on the motor and remove it, should I put a couple of 2x4's up on the top of the slide (as slide locks) to prevent it from sliding out on its own either from gravity or wind until I get the new motor installed? Any suggestions would be greatly appreciated. This is a Power Gear Slideout Room System.