Proper Hydraulic Fluid to use?

WHERE did you read not to use Dextron 3. Motorhome Hydraulic Jack/slide systems ALL use Dextron 3. From the Kwikee owners manual. Doug

1. Be sure the leveling jacks are in the retracted position. Remove the breather cap
on the reservoir and check the fluid level in the reservoir. The fluid level should be
approximately 1" below the top of the reservoir. This standard provides an adequate
amount of fluid for the levelers to operate efficiently. If the fluid is below this level, add a
sufficient amount to bring the level up to the operating standard. When filling the
reservoir, use transmission fluid only. We recommend Dextron III. Do not mix fluids.

Stop thinking of this as an RV item that needs repaired. The cylinder is no different that that is used on a backhoe, front end loader, dozers and such. Getting it repaired shouldn't be a problem. Just keep in mind that shop service might cost around $100 an hour so there is a point when replacement is a more economical option but you won't know unless you try.

When I had an internal leak by, jack would extend and retract but would not lift the coach, I open a Google Map of my area (southeaster Virginia) and search for "hydraulic cylinder repair". Returned a dozen of possible sources to investigate within a 45 minute drive.

I removed the jack, four bolts and two hydraulic lines, drove down to the closest shop. They said no problem, shop service is $X per hour and shouldn't be more than 2 hours with $X for material. A few days later they call as the jack was ready. Reinstalled and cycled the jacks for full retract to full extent a few times to bleed any air and all was good.

Hydraulics are used in many industries. Search for shop that specializes in that equipment. You might need to remove/replace it yourself, or hire somebody else to do it.

Farm equipment repair, ask around the local co-op

I wish I had one close by, I could get my powergear curbside rear jack repaired

Yeah, don't use the stop leak fluid.

Try to find a repair shop that does automotive hydraulic lift repairs.
They can take you jack and find a seal that works.