I have experience with repairing my own slide out. Without knowing what slide out you have exactly, its tough to trouble shoot, but here is what I know and it may help you.
Nearly ALL slide out components are made by the company Lippert Components. They can be very helpful and are willing to help you solve your problem. I am not affiliated with them, I've just had excellent experience in dealing with them for repairs. Here's a link to their customer service page:
If you have the book for your RV, try to find the section about your slide out. Many slide outs have a manual override. Mine does not, but many do. Learn how to use it in case you get in a jam. Because of the gear reduction on the motor, they are very hard to move by merely pushing on the slide out itself.
Your slide out will have a "brain". That module will have flashing lights that give you a trouble code. Usually that trouble code is printed on the outside of the box. Mine is located in one of the outside storage compartments, upside down, a real pain to get into a take a look at. You will need to do this though when/if you call Lippert for help.
By the sounds of it one of your motors is going out on you. They're very small 12v motors that have one heck of gear reduction on them. Your only source, as far as I can tell, for a replacement is from Lippert. My slide out was doing the exact same thing as yours.
If I was you, I would give them a call. They will be able to guide you in solving your problem and they're happy to do it. I hope this was at least a little bit helpful and you can get your RV back on the road.