Yes, it sounds like a solenoid issue. I think all three solenoids are the same. Have you tried moving one of the rear solenoids to the front solenoid location? First, determine that you have power going to the front solenoid when the panel is operated. If not, solve the power problem first.
You can also swap wires between the solenoids (make yourself an original wiring diagram first) to help with troubleshooting. [When I first got my 2000 HR endeavor, the solenoid wiring was backward between the left and right rear jacks because someone had installed the wires incorrectly...so I know you can swap wires between the solenoids without damaging anything.]
The link below is a parts and service manual that probably includes your version. Maybe it will be helpful.
I believe that Power Gear will not accept orders for parts from non-dealers, so you will have to find an rv place to order for you. Once you know the part number, search E-Bay as there are some Power Gear parts on E-Bay.