just 2cts here... i bought my gal a sailrite lz1 for a present a couple of years ago... she went thru all manuals videos etc. but, for sure w/ in a short period of time on any project (cushions, sail patches, canvas stuff), she would start swearing at the machine as it would go out of whack and need adjusting.
finally while we were stuck in the DR for engine issues, we met another couple who had a Sailrite, and together they worked thru several issues w/ the machine(s), that's right their machine had similar issues. We were lucky enough to find a guy that was a commercial canvas guy, who had several of these machines. He informed us that you had to constantly adjust the machine when doing heavy work, otherwise it would slowly go out of whack.
Long story short, a couple of weeks later we sold the machine to a guy in PR
who owned a fabric store. We bought a commercial/professional grade Singer that happened to be on sale at Walmart!!! They just wanted it off the shelf. It came w/ a walking foot as well. My gal LOVES it!!! it is easy to use, lighter, 4times cheaper, and so far has done everything we need it to, including canvas.
My point here is not to bash Sailrite. We did meet another guy who loved his, and he did quite a bit of work for himself and other boat buddies. my (our) point is that you don't necessarily have to go w/ an old, or expensive machine. Heck if ours breaks in a year I won't mind dishing out the money for another one. I can do that 4 times over a decade probably and have two things. HAPPY sailing gal, and cool stuff on the boat!