It sounds like your slide solenoid may not be working correctly. Not sure about your model, but on ours it is located in the rear-most compartment on the passenger side and is well labeled. The two large wires on it pass power to the electric slides. You can short those two wires in an emergency and I have also just whacked mine with the handle of a large screwdriver once the ignition is on while waiting on a new solenoid, but a replacement is in order.
If you don't know about it, the
Tiffin RV Network web site has a great forum (link on the left side of that page) which is a wonderful resource for Tiffin owners. It has no relationship with Tiffin Motorhomes but is ran by other Tiffin owners and has great members sharing info making everyone's life simpler.