On my new slide, that does the same sound as you describe when it's open and closed (it still works and I have not experienced it not working yet), but I have zero access to it from the top inside the slide.
I'm not sure how I would access it if it was fully in either? The bottom is sealed. When it's open, I can see the arms and the gear rack, but have never really looked for the motor on it... I should do that before I pull it in..
I was told I could open/close it manually with a hand crank and it's on the opposite side of the trailer. I've never used it, or really looked, other than I have the crank and know where it's located...
Sorry, no further info, but I will be checking this out myself now!! I figured I had a shear bolt, but never really thought about where it is or how to replace if it's in..
Good luck! Mitch
