I have a Howard system on my 94 Marathon and like it a lot and use it all the time on the road.

Sorry to hear they are out of business. Mine has signs of some leakage around the hydraulic cylinder too, but that does not affect the operation as long as there is still fluid in the system. besides being messy if it is a big leak. As long as you are not adding much fluid, like say a pint every oil change interval, a small leak will not matter much.

If you want to fix it, any hydraulic house will be able to rebuild the cylinder with new seals fol very little money. Presumably the rest of the system will keep working.

I do have the operation manual that came with my coach in case you need a copy.