How can i access the drive unit for the bedroom slide on my 2009 Forest River Flagstaff Classic Super Lite FKBSS?

find tank see bottom of tank see drains if there at all.
if not we pump it dry

Here is a video that shows you haw to work your slides manually if the power source fails. Hope this helps

How To Override Your Slide Out Mechanisim

http://www.forestriverforums.com/forums/sitemap/f-29.html

Try this site https://searchmanuals.net/search7/?keyword=%2Bowners+%2Bmanual&gclid=CjwKCAiA8OjjBRB4EiwAMZe6y5_84V3ek15m17m45ZjUS8CJGN8CDmLdMHFmDUai5BTqkctyGuc0KBoCV8sQAvD_BwE

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I have seen disconnected wires in pictures of used units. It may be for uninstalled options. Unfortunately, it seems like mfg don't want you to DIY repairs so the best you can do is make your own diagram.

Well, as you probably already know Forest River only carries the on-line manuals for the last three model years. However, I'd send them an email request and see if they can dig one up out of their archives.
Another good place to try would be owners group forums.

You will not find a plumbing diagram since they are not published. Were you connected to the city water or were you using the fresh water tank? You will basically have to start at the input point and follow the water lines until you locate the leak. Identify what is leaking and replace. It is possible that a water fitting has either popped loose or cracked from freezing.

If this is a 5th wheel, two sneaky places manufacturers have been known to put them is either under the tread of the step going to the bedroom or look behind the bedroom door.

Do you have a tank heater on the tank? If not, you may want to get one to prevent the tank from freezing and busting. Next, there is a small diode inline and it may have failed which will give a false reading.