I have been using my Landis 30 for the last 5 years. It is a shoe repair machine. My landis is a bit finicky. I was able to purchase a blade from Pilgrim Shoe and sewing machine company. but unfortunately they were bought by USM-Americas.com due to retirement of the owner. I would give them a call and see if they still sell parts for the landis 30. I paid $88 for a blade back in 2016.
I do split oil tan, chap leather, veg tan and English bridle with mine. The key to setting up your machine is to make sure the top roller is even on each side. I do it by eye. Might be able to use a feeler gauge to help make sure its even. My splitter also likes a fair amount of pressure from the top roller. I do find when I switch blades it will have to adjusted since each blade is a different length. The thinest consistent I've been able to split down to is 2oz. Sometimes it will get down to 1 oz but it is hit and miss. Keep your blade sharp and don't split a large amount all at once or the blade/knife will crack. I sharpen my blades with a stone.
I don't know of any splitter that will go down to 1 oz. I believe the cobra splitter which is modeled after the landis 30 will split down to 2 oz. They are guaranteed for life which will be my next purchase.
Who ever you send your blade to for sharpening ask them if they make blades. Some saw filers that sharpen blades also make them.