There's some troubleshooting info for Power Gear jacks at the link below:
Fleetwood Tech Library - Power Gear
You may have to hunt a bit to find your system.
I looked on that web site an found troubleshooting for 2004 and later, but nothing that I could find for a 1999 motorhome.
I have a 2000 model with power gear jacks, and I have saved a troubleshooting document for the older models. If you need it, send me a private message with your email address and I'll email it to you.
Some of the items in the older troubleshooting guide are
each solenoid has a fuse in the red line within 18 inches of the solenoid.
A stuck dump valve can cause the problem you have.