Lead Landing Leg not working

No need to shop a third party vendor. Go right to the mfg web site. Likely the pin that holds the bevel gear has sheared or the bevel gear has broken a tooth. Both are an easy fix. If there is a metal cap on top of the leg, pop it off. On the underside will be all the information you need to get repair parts.

If it isn't the bevel gear, which is the most likely culprit, then it probably is the screw itself, or the insert the screw turns in.

While packing up this AM I noticed the transmission isn't attached to the leg at all looks like pin coming out of transmission and into the leg sheared. I guess only question is if that is the whole issue or did it shear for other reason.

Sorry noticed sig is wrong we are talking about a 2003 Montana fifth wheel

The failure is likely due to over extending/retracting the leg. They only have ~19" of travel. You should mark the legs so you can see when you are getting close.

Your legs are made by Venture Manufacturing and they are very helpful as well as price competitive. Their web page offers a number of documents about their legs.

Here is a link to a diagram of the pieces parts of the leg assembly. Clicky

There are four possibilities of what the problem could be. There are two pins, one in the horizontal shaft bevel gear and the other for the bevel at the top of the screw rod and either one could break and cause the problem. Also the bevel gear on top of the screw shaft could be stripped. And lastly the thread block that the shaft turns in could be bad.
This past summer I damaged the bevel gears on the follow jack and it made a loud thumping sound. I order a kit to replace the gears, but some how the screw shaft had a bigger hold dia. then the replacement. I tried everywhere I could think of calling both the trailer and frame manufacture and nobody could direct me to the right parts. Finally had to replace entire jack assembly to correct problem. I now have put a red line on near the top of the extension tube so I know when to stop retracting the legs.
If you need more information on how to take the legs apart or replace them, send me s PM

So after following links and reading I now understand that the rebuild kit is really parts in the top of the leg, I thought they were for the Transmission.

So I have a rebuild kit on the way. Doesn't look to hard to replace the parts. Luckly we are here for the month, so I have time to get it fixed before out trip back east in early Nov.

Please come back and follow up on the initial problem. It's always good to know how the whole situation plays out. And it gives us another data point when the problem pops up again on someone else's trailer.

I got the rebuild kit and did the job yesterday.

Taking the leg off was pretty easy and is necessary to put the new parts in. Mine is mounted with 2 brackets that are basically U's with bolts through them. I removed the 2 bolts and the leg was able to come out. As mentioned earlier, the pin going from the transmission into the leg was completely sheared so it wasn't an issue when removing the leg.

I also removed the transmission and motor. That was 2 wires. And a small bolt and nut, that goes through the crossbar that drives the other leg.

The original pin that runs through the transmission and into the leg was twisted and sheared. It took a bit to get the old one driven out of the transmission because of the twisting.

As for putting the new parts in the leg that was pretty straight forward. I found downloadable instructions and an image of the parts here https://www.strombergcarlson.com/download/Venture_landing_gear_rebuild_instructions_07022015756am

As predicted the reason mine was sheared was the leg had been ran in to far. I tried using a screw driver to pry the old gears enough to get the leg moving but didn't have any luck.

With the parts removed, you basically have the top of the jack screw that runs though the leg sticking up. A Pin goes through this and is what the gear sets and and drives the jack screw. I made a "tool" with a deepwell socket and my angle grinder that would slip over the jack screw and had groves that the pin could set in. With my "tool" and a rachet I was able to get the jack moving again. Once it had turned a couple of times and gotten back on its normal threads it moved fine.

putting the parts back in the leg was straight forward. The hardest part of the job came with getting the leg back in the RV. Remember when taking it out the pin going through it was sheared. Putting it back I had an pin sticking out of it an extra 4 or 5 inches and that was enough to make it hard to maneuver the leg in. I had to take the foot off of it and the pull pin mechanism for the dropleg and feed it in from the top. With the leg retracted as far as it would go.

Once you get the leg back in. Make sure you EXTEND THE LEG THE SAME DISTANCE AS THE OTHER LEG before you reattach the transmission and crossbar. Otherwise you have to take the transmission back off and get the legs to match. Don't ask how I know that ;-)

I plan to get a bit of reflective tape, and put on the legs to indicate how far that can be retracted. I also plan to not left my wife help setup the trailer in the future ;-)

Any questions that I didn't cover please let me know

Thanks for coming back. It's always nice to hear how these things turn out.