I just went through some of these problems with our '17 Cardinal's hydraulic landing gear. When consulting LCI Lippert tech support, they pointed the trouble in the direction of the right front lead landing gear spade valve. After installing a new one, the trouble still was there. Next they had us check the voltage drop at the double polarity solenoid. Having replaced that, (trouble still there) they had us check the continuity of the wiring harness to the lead landing gear. After confirming that the harness was good, they had us order a new control module.
Installed the new control module and everything works as it should. As it turns out the excessive voltage drop from the dual polarity solenoid was due to a defective control module and NOT the lead landing gear spade valve or the dual polarity solenoid, causing the spade valve not to fully open or close while extending or retracting the slides/jacks. (We decided to keep the new parts for added insurance).
Lesson to learn is to check all electrical connections, voltage drops, continuity, battery voltage, etc through out the system before just replacing parts.
If you need a new control module, you'll have to re-zero the level system. Easy to do but first level your rig by using manual commands to level using a 4' carpenter's level (front to rear, side to side) then re-zero the system. To re-zero, go to You Tube and look it up: very easy to do. Hitch up and retract everything with slides in, then extend front landing gear, un-hitch then do the auto level. And of course operate the slides. In our case the jacks/slides seem to work much better.
FYI: when we ordered the new dual polarity solenoid, we found it cheaper (exact part#) from Amazon. The price was $86 vs. $156 through Lippert; and Amazon had it to me in two days, whereas Lippert did not have it in stock. It would be there at Lippert in 7 days, then ship to me in an additional 3 days. Amazon did not have the spade valve or control module.
Lippert tech support is good help, but these issues took time (days) and when you call in a second or third time you may get a different tech to help you. Just be sure to fully explain what's happening and what you've done to correct it, step by step.
Good luck and let us know what it took to fix it.