It seems to be a problem internal to the drive unit, but we can't figure it out.
Your SIG indicates you have an '07 Fleetwood so presumably you're aware Fleetwood issued a recall for it's power lift system?
and search for recall 07V464000 for more info. Although your E2 isn't on this list I'd be suspicious that this recall still may apply because the lift motor that is the subject of this recall is a Barker, and even though you may be beyond your first year of warranty coverage on the trailer itself this recall may be covered anyway. That being the case there's little reason to try to fix this yourself ... make it your dealer's problem.