I have a MM 2106DS, I was told by the RV Salesman that my unit had a manual overide that would retract the slide out should it fail. I searched a few of the Winnebaqo web sites for information and find out after contacting Winnebago directly that my unit does not have a crankable overide for the slideout. The 2106DS from previous years did, but for my 2018 trailer I have to undo the two slide motors from the outside, then I have to go inside the trailer and pull back the rubber seal which is at the top of the slide out and which covers the two motors, There is one motor on each side of the slideout, I then have to pull the motors up do that they no longer engage the gears. Then I can manually push the slide out back into the trailer. Note that my 2106DS MM has the smaller slideout, I am advised that the larger slideout do have a crank mechanism. So you really should contact Winnebago directly and ask which slideout mechanism you have.
Search YouTube there are videos for the various slideout, note there are a number of different slideouts so finding yours may mean contacting Winnebago directly, you just need your serial number and VIN number and they can look up the specifics for your trailer. As I said components have changed over the various model years.