Sorry to say this lock is no longer made and parts are not available. Some of us have managed to fabricate parts as they have failed. I haven't read of anyone else who has had the lever break. Can you use your deadbolt to lock to motorhome and use broken lock as just a latch? That is what we do.
Search the Motorhome knowledge base and you'll read lots of tails of woe.
Inland RV sells a kit to install a smaller lock that is still available. As I understand it, you need to add some sheet metal to the door because the existing cutout is larger than new lock.
If you want others to be happy, practice compassion.
If you want to be happy, practice compassion - The Dalai Lama
1984 310 Limited Motorhome
Courtesy Parking (W/S/E/Wi-Fi) on I-5 in Northern California, 70 miles from Oregon border