There is only one hydraulic pump (battery compartment) but several control valves and check valves in the legs.
People have had success having them rebuilt rather than replace them. Far cheaper.
Download the MYLCI app from Google play store. It has all the manuals and troubleshooting procedures. You can go through the steps to check out the Hydraulic system to isolate the problem. Bad jack, bad check valve, etc.
There are also some manuals in the files section at the top of the webpage
https://www.montanaowners.com/forums...hp?do=cat&id=3