When they say a lifetime guarantee at Leather Machine CO. they mean it anytime I've had a problem. They help immediately and send any Parts needed are sent that day . The other company I bought a machine from you send an email or leave a message and they'll get back to you in a few days maybe
You have to use as large a needle as needed without catching. You can also run it through some thread Lube. When you're all done take a flat shoe hammer or something with no marks on it and tap the stitches all the way around. It'll set everything and closeup the holes
Panhandle Leather https://panhandleleather.com has piping if you don't want to make your own. They sell a lot of boot making supplies.
Sailrite https://www.sailrite.com has a lot of Upholstery supplies that can cross over to leather work.