There won't be a separate fuse for the two motors as both of them are on one controller using the same fuse. If you only have one motor working, then you have a defective motor or open/short in the wiring. Just FYI, the circuit breaker for the slides is actually in the front DS outside compartment.
Here's another thread where someone is dealing with the same issue and I posted a troubleshooting document on that thread.
https://www.irv2.com/forums/f106/sli...ng-534912.html