You don't need to raise it high to get the leg out. You lift it out the top, not drop it out the bottom.
That's correct. You'll have to support the frame near the leg you are replacing or just hook it up to the truck. Once the holding bolts are removed, you can pull the leg out through the door hatch. Then just reverse the process to install the new one. The more challenging part is lining up the motor mechanism with the leg screw so they engage properly... otherwise it's pretty straightforward.
I just did this two Sundays ago. One tip for you. Even with the screws removed, the steel clamps will still be tight. A block of wood and a mallet helped initially, but ultimately what worked best was a ratchet strap around a clamp and connected to the truck’s trailer hitch. Just ratchet a little at a time till you can pull the leg out from between the clamps.
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2017 Eagle HT 26.5BHS Sold
2019 Eagle 321RSTS Sold
2024 Grand Design 310GK
2024 Chevy 3500HD DRW
Some members have mentioned spraying CRC Powerlube up the landing gear with the foot removed and have had good results. I was thinking about how to get the CRC up near the top of the gear. Came across this and wondered if it would work. Pushing the tube up the shaft would probably plug the tip with existing grease. Siliconing the tip to the CRC can nozzle would prevent it from popping off from back pressure until the tip clears: