Sounds like you 378 is trying get itself stuck in the mud.
With the rams bent taking the hoses loose wont help getting the jacks out from under the MH, their wedged in.
You probably need to invest in a floor/bottle jack that can lift/hold the MH. It's going to shift when you take the levelers off.
Be VERY careful when taking them off.
Try to get them fixed should be MUCH cheaper than new.
The one hose I've replaced had a hole in it so the pressure was already gone, maybe someone with experience taking a pressurized hose off will see this.
After you get the rebuilt/new jacks on all you have to do is add a little fluid and cycle the jacks a few times, the system is self purging.
Here are some links.
Strongway Hydraulic Bottle Jack — 12-Ton Capacity, 9in.–18 5/16in. Lift Range | Bottle Jacks| Northern Tool + Equipment
Good luck and keep us updated