Here is the manual for a Suncruiser with a 1 in the serial number:
Manual
Do a search on Slideout in the manual and everything you never wanted to know is there.
My past experience with Winnebago slides.
There is a master room lock for the slides that has a key in it. It is labeled off and on. Trust me on this, on does not necessarily mean that the key is all the way to the detent position. Turn the key off and then back on again. Some one could have bumped it. Try try the slide.
You definitely have to clear the drain slide lock. It is on the outside of the MH. Looks like a little dimple with a hole in it near the top of the MH. A pipe cleaner or smaller diameter item will work.
Also, up in the cabinet will be the slide lock. if it is a very long slide there may be two of them near each end. If there is any debris, or there is a malfunction of that lock the slide will not open.
Remove the plastic cover over the slide lock. Have someone press the unlock button and see which way the shaft turns when unlocking. With a pair of channel locks or vice grips see if you can turn that bar in the same direction of unlocking. If it moves a little, try the slide again. Also inside the plastic case check the bolts and washers. I had a bolt that was to long that the motor shaft was rubbing against and caused a lock washer to split in half. Lot of power on those little motors.
After my fix fo the broken lock washer I never used the lock switch again except one time in a high diagonal wind that wanted to move the slide a little. The wind was about 45 mph. Next time I'll stop instead of continuing on.
Just a few suggestions that you may have already tried.