Mantis just needs new hoses and the old pump setup for the weapon to work.
Unfortunatly that original died in a demo with Tough As Nails.
The replacement setup was a failure as the O2 event demonstrated.

Pumps, any decent hydraulics shop has sets that are used for tailgates and such.
Seperate pumps can be coupled to any motor with a suitable rpm range.

Andy, maybe you can source an original setup for Mantis. At least we can reactivate the weapon.